Scientific American, October, 1974

SCIENTIFIC ERIC

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© 1974 SCIENTIFIC AMERICAN, INC © 1974 SCIENTIFIC AMERICAN, INC Cars are like people. as is a 4-speed transmission, plus front and rear Some seem filled with inhibitions, concessions, stabilizer bars in the suspension. compromises. And to further demonstrate its utilitarian talents, Then there's the other kind. The kind that exudes Skyhawk is a hatchback. Which opens to reveal charisma. Confidence. Free spirit. seating for four, a generous luggage compartment, Buick's new Skyhawk, as its name suggests, is of an expanse of natty houndstooth upholstery and a the latter category. big tachometer. All standard, of course. It sits there, rakish and purposeful, square There's more, but space limits. Suffice to say if headlamped and aerodynamic, tautly suspended you've stayed with us this long, you're probably the on its radial-shod wheels. Like any confident design, kind of person Skyhawk was designed to attract. Skyhawk does not beg you to love it. It does In which case the two of you really not over-promise or boast. It simply is. And its pres ought to meet each other. ence inspires affection. At your Buick dealer. Yet for all its machismo, for all its tendency to look like some exotic European prototype, Skyhawk is as untemperamental as an old friend. Its engine is a Buick-built, 3.8 liter V-6 that is designed to be both responsive and frugal. High-Energy Ignition (no points or ignition condenser to replace) is standard,

Established 1845 AM E RI CAN October 1974 Volume 231 Number 4

ARTICLES

21 TIlE INTERNATIONAL CONTROL OF DISAR\lM1ENT, by Alva Myrdal An agency is needed to disseminate arms information and verify arms agreements.

34 THE STRUCTURE OF EMISSION NEBULAS, by Joseph S. M iller Dye-transfer color prints show the distribution of ions in light-emitting nebulas.

44 HOW CILIA MOVE, by Peter Satir The hairlike appendages of living cells are molecular machines powered by A TP.

64 NITROGEN FIXATION, by David R. Safrany Thermodynamics and economics rule ways of making nitrogen form compounds.

82 THE DIMENSIONS OF STAIRS, by James l\1arston Fitch, John Templer and Paul Corcoran How stairs are designed should follow how they are used.

92 MIMICRY IN PARASITIC BIRDS, by Jiirgf'1l Nicolai The widow birds of Africa are among those that lay eggs in other birds' nests.

100 THE COORDINATION OF EYE-HEAD l\10VEi\lENTS, by Emilio Bizzi How these interrelated movements are synchronized is investigated in monkeys.

110 THE EXCAVATION OF A DROWl\EDCHEEK TEi\IPLE, by Michael H. Jameson A shift in sea level preserves a site for shallow-water archaeology.

DEPARTMENTS

6 LETTERS

13 50 AND 100 YEARS AGO

14 THE AUTHORS

55 SCIENCE AND THE CITIZEN

120 MATHEMATICAL GAMES

126 THE AMATEUR SCIENTIST

135 BOOKS

142 BIBLIOGRAPHY

10 A R 0 OF EDI TO It S Gerard Pie! (Publisher), Dennis Flanagan (Editor), Francis Bello (Associate Editor), Philip Morrison (Book Editor), Trudy E. Bell, Brian P. Hayes, Jonathan B. Piel, David Popoff, John Purcell, James T. Rogers, Armand Schwab, Jr., C. L. Stong, Joseph Wisnovsky

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PUBLISHED MONTHLY BY SCIENTIFIC AMERICAN, INC. , <415 MADISON AVENUE, NEW YORK, N.Y. 10017. COPYRIGHT © 1971 BY SCIENTIFIC AMERICAN, INC. A LL RIGHTS RESERVED. PRINTED IN THE U.S.A. NO PART OF THISISSUE MAY B!; REPRODUCED BY ANY MECHANICAL, PHOTOGRAPHIC OR ELECTRONIC PROCESS, OR IN THE FORM or A PHONOGRAPHIC RECORDING, NOR MAY IT BE STORED IN A RETRIEVAL SYSTEM, TRANSMITTED OR OTHERWISE COPIED FOR PUBLIC OR PRIVATE USE WITHOUT WRITTEN PERMISSION OF THE PUBLISHER. SECOND-CLASS POSTAGE PAID AT NEW YORK, N.Y., AND AT ADDITIONAL MAILING OFFICES. AUTHORIZED AS SECOND-CLASS MAil BY THE POST OFFICE DEPARTMENT, OTTAWA, CANADA, AND FOR PAYMENT OF POSTAGE IN CASH. SUBSCRIPTION RATE: $12 PER YEAR, U.S., POSSESSIONS AND CANADA; $15 PER YEAR, ALL OTHER COUNTRIES. EUROPEAN SUBSCRIPTION COPI�5 MAILED C/O PUBLICATIONS DISTRIBUTION SERVICE, ST. KATELlJNEVEST 1<4 , 82000 ANTWERP, BELG IE.

The photograph on the cover, made with the 120-inch reflecting telescope at the Lick Observatory, shows the central region of the Great Nebula in Orion. The photograph was made by the dye-transfer process, in which three black-and-white negatives made through color filters are combined to produce a color print. Such a print reproduces colors more accurately than standard color emulsions do , and therefore better distinguishes the wave lengths emitted by the various kinds of atoms that make up the nebula (see "The Structure of Emission Nebulas," by Joseph S. Miller, page 34). The four bright stars in the center of the nebula are known as the Trapezium. The luminosity of the nebula is mainly due to the brightest of the four, the energetic photons of which ionizes the atoms of the tenuous gas around it. The green glow is radiated by doubly ionized oxygen atoms, that is, atoms from which two electrons have been removed. The three bright stars to the southeast (lower left) d o not appear to contribute to the ionization.

THE ILLUSTRATIONS

Cover photograph by Joseph S. Miller, Lick Observatory

Page Source Page Source 22-23 EROS Data Center, U.S. 50 Peter Satir, University of Geological Survey, De- California at Berkeley partment of the Interior (top); Fred D. Warner, 24-33 Graphic Presentation Syracuse University Services, Inc. (bottom) 35-37 Lick Observatory 51 Keith E. Summers, Na- 38-42 Allen Beechel tional Heart and Lung Institute (top); Georg!;) 44 Ellen R. Dirksen, Univer- V. Kelvin (second from sity of California at San top); Charles J. Brokaw, Francisco (top); Birgit California Institute of Satir, University of Technology (bottom) .i' California at Berkeley (bottom) 52 Peter Satir (left), George ALMADEN V. Kelvin (right) 45 George V. Kelvin SOlERA 46 Peter Satir, University of 64-80 Lorelle M. Raboni California at Berkeley 83 Sol Mednick SHERRIES (top); George V. Kelvin 84-85 Ralph Morse (bottom) 86-87 nil Arbel Almaden Flor Fino,1ight and 47 Birgit Satir, University of bone dry, the perfect aperitif. California at Berkeley (top 88 Ralph Morse Serve chilled. left and center); Peter 90 nil Arbel Satir, University of Cali- 92-97 Tom Prentiss Almaden Cocktail Sherry, delicate, fornia at Berkeley (top pale and dry, delicious on the 101-106 Alan D. Iselin right); George V. Kelvin rocks. (bottom) 110 Julian and Eunice Whittlesey Almaden Golden Sherry, nutty 48 George V. Kelvin (top); 112 Michael H. Jameson, Uni- and medium dry, appropriate Peter Satir, University of versity of Pennsylvania before, during or after any meal. California at Berkeley (bottom) 113-117 Eric Mose Almaden Cream Sherry, rich, soft 118 Michael H. Jameson, Uni- 49 Peter Satir, University of and moderately sweet, delight versity of Pennsylvania California at Berkeley ful with cheese and fresh fruit. (top); George V. Kelvin 120-125 lIil Arbel AlmadenVineyards, Loa Gatos and Paicines. California (bottom) 127-130 Jerome Kuhl

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© 1974 SCIENTIFIC AMERICAN, INC Dressler. Yale University Press , 1964.) However, Judge Bazelon demonstrates LETTERS this in his article. The mere existence of his own Appellate Court affirms the Don't give legal position that "the definition of an [due process] and the appraisal of its ordil:\ary Sirs: adequacy are matters for [judicial] de mar� In Judge Bazelon's article ["Psychia termination." Yet he misrepresents the trists and the Adversary Process," by comparable position of the American ,�""",-""",- David L. Bazelon; SCIENTIFIC AMERI Psychiatric Association as "an adamant CAN, June] he fails to point out that the statement of what I must call profes adequacy of the adversary process to_ sional mystique." achieve justice is controversial within the Another distortion is his disingenuous legal profession, and that the verdict characterization of Rouse as "a patient often goes to the most skillful lawyer confined without his consent [who] sued rather than the party with the just cause. for release or for adequate treatment of Nor does he say that the acceptable his disability." This half-truth omits that methods of this process include "distor when arrested, 1S-year-old Rouse was tion (if not misrepresentation) and the carrying a fully loaded A5-caliber pistol, manipulation of bias [which] defeat[s] several hundred rounds of ammuni the possibility of finding truth or reality." tion, two electric power drills, hacksaws ("Lawyers, Truth, and the Zero-Sum and other "home hobbyist" equipment. Game." James Marshall in Notre D ame Rouse's mother insisted that he had been Lawyer, Volume 47, pages 919-926; mentally ill for some time and needed April, 1972.) Nor that "the objective of treatment, not jail. The reader is not told each lawyer is to win his client's case at that Rouse was acquitted on the grounds any cost. ... The principles which under of insanity and that the law mandated his lie what is being fought about become hospitalization. Nor does Judge Bazelon relatively unimportant. What is of su tell us that Rouse had been showing un preme importance is to win." (Trial by equivocal improvement in group therapy Combat in American Courts. David when he refused further treatment. Nor are we told that the hospital staff and the lower-court judge tried to persuade Scientifie American, October, 1974. Vol. 231. No.4. Published monthly by Scientific American, Rouse to continue the effective group Inc., 415 Madison Avenue, New York. N.Y. 10017; Gerard Pie!, president; Dennis Flanagan, vice therapy, nor that the case was heard after president; Donald H. Miller. Jr., vice-president a year of persistent refusal of treatment. and secretary; George S. Conn. treasurer. Arlene Wright, assistant treasurer. Judge Bazelon tries to convince the Editorial correspondence should be addressed tn reader that psychiatrist witnesses ob The Editors, SCIENTIFIC AMERICAN, 415 Madison Avenue, New York. N.Y. 10017. Manuscripts DTC struct due process, as if they could re submitted at the author's risk and will 110t be returned unless accompanied by postage. quire lawyers and judges to abrogate

Advertising correspondence should be audressed their legal skills or knowledge. Sworn to Harry T. Morris, Advertising Director, SCIEN. TIFIC AMERICAN, 415 Madison Avenue, New York, witnesses must answer all legitimate N.Y. 10017. questions put to them with "the truth, Offprint correspondence and orders should he addressed to W. H. Freeman and Company, 660 the whole truth, and nothing but the Market Street, San Francisco, Calif. 94104. For truth." If they do not, they face con each offprint ordered please enclose 30 cents. tempt or perjury proceedings. However, Change of address ( or other subscription cor· respondence) should be addressed to Circulation judges do sit quietly while lawyers ne Manager, SCIENTIFIC AMERICAN, 415 Madison Avenue, New York, N.Y. 10017. Please notify us glect to ask crucial questions or to ob four weeks in advance of change. If possible, kindly furnish an address imprint from a recent ject to improper ones. Both sides use issue. Send both old and new addresses or com plete and mail Post Office Form 3578. psychiatrist witnesses and the jury de termines which side presents the more o Please enter change of address. reasonable and more credible testimony. o Please enter subSCription. U.S. and Canada: Judge Bazelon focuses on the failure 01 year, $12 02 years, 822 03 years, S30 All other countries: of his Durham rule as a case in point. SIS 02 27 03 837 01 year, years, $ years, Here too we get half-truths. In a law NAME journal article, whose audience is more sophisticated about the realities of the NEW ADDRESS law, Judge Bazelon admitted that the poor "quality of the legal representation available for indigent defendants" was implicated in the failure of the Durham OLD ADDRESS rule, although he does not even hint at it here. ("Implementing the Right to Treatment." David L. Bazelon in The University of Chicago Law Review, Vol ume 36, pages 742-754; Summer, 1969.)

1936: Mercedes-Bent introduces theworld's first production Diesel passenger car.

We've soldwell over a million Diesel automobiles more than 60,000 in America alone. What we've learned is that before you offer'a Diesel to the world, you'd better know exactly what you're doing.

N 1936, the world's first series Diesel power introduced new ments are among the reasons why: I produced Diesel passenger car economy and reliability to the au 1. Multistage fuel injection. rolled out of our Stuttgart, Ger tomobile. It also fostered new prob With this system, the injection many, plant. The experience we lems. Some manufacturers judged nozzles and pump vary the amount have accumulated since then has the enigmas greater than the re of fuel entering the combustion paid dividends. wards. Mercedes-Benz was not one chambers to meet load conditions. The Mercedes-Benz Diesel of of them. 2. Precombustion design. today is a motor vehicle unique in We alone held to our convic Two interconnected chambers are all the world. It delivers extraordi tions concerning the Diesel, refin used for each cylinder. Air and fuel nary mileage. Its durability is leg ing it year by year over the past are mixed and burnedin two stages, endary. And it already meets the four decades. providing a longer power pulse for tough 1975 Federal clean air stan Today, our Diesel engines are smoother running. dards for automobile engines. unique. Two sophisticated develop. Result: uniquely smooth, quiet,

© 1974 SCIENTIFIC AMERICAN, INC clean-burning Diesel power. get about tune-ups. Diesels need if you had bought a 220D two years Engineering advances like these no spark plugs, no points, no dis ago, it would now be worth over take years to perfect. Small wonder tributor, and no carburetor. 90% of the price you paid. If your that the specialized development Diesel were now three years old, it of Diesel automobiles has discour would still have retained more than aged other manufacturers. Why has 80% of its original value. Mercedes-Benz alone consistently An absolute nonconformist championed the idea of the Diesel passenger car for so long? Consider Obviously, the Mercedes-Benz the following: Diesel is an iconoclast in its ap proach to modem driving prob Extraordinary fuel economy lems. Like all Mercedes-Benz auto In a strictly supervised test con mobiles, it carries its dissidence to ducted by Motor Trend magazine, a every element of its construction. 240D -even with automatic trans The Mercedes-Benz 240D is a mission-recorded an honest 24.4 full 5-passenger sedan. It has in miles per gallon. Th is test was a terior space and trunk room on a No conventional ignition or combination of actual urban and par with the finest domestic luxury carburetion systems -no tune-ups, highway driving -no "economy cars. It has disc brakes on all four ever. And parts that aren't there run" or "proving ground" tests. wheels. It has a separate suspen can't break down. No full-sized sedan, foreign or sion system for each wheel. It em domestic, delivers this kind of mile Amazing resale value bodies the decades of safety inno age. And even the domestic mid vation and advanced engineering There is one area where a Mer sized sedan which came out best in that are so much of the Mercedes cedes-Benz Diesel is just like any the Motor Trend tests was still n ear Benz philosophy. other Mercedes-Benz. Resale value. ly 30% behind the Mercedes-Benz If you seek exceptional mile The automobile industry's most au 240 Diesel Sedan. age, maintenance economy, de thoritative sources agree that any pendability and resale value-with Mercedes-Benz has a better resale out the "economy car" penalties How to avoid being value than any full- or mid-sized ® that usually go along a guinea pig sedan made in America. with them - it's t ime t o Because the 240D is so new, Buy a Mercedes- Benz Diesel. consider a Mercedes- we alone have sold and serviced there has not been time to gather Benz Diesel. Diesels in America for over a the proven figures which previous decade. For us, Diesels are hard Mercedes-Benz Diesels can boast. ly a novelty. Highly skilled me But consider the history of the Mercedes-Benz chanics f amiliar with our Diesels 220D, the 240 Diesel's immediate Engineered like no other car work in our 390 dealerships all predecessor. As an average owner, in the world. over the U. S. So, when it's time for the little routine maintenance your Mercedes-Benz Diesel re quires, you're an old f riend, not a guinea pig.

Another plus: because Diesel fuel is often less expensive than gasoline, Diesel owners get more miles from cheaper gallons.

Economy car Operating economies depend on far more than fuel appetites. Peri odic maintenance and reliability are equally critical. How does the Mercedes-Benz Diesel measure l.lp? Any car needs some routine servicing, but with a Mercedes-Benz Diesel you can for- 1974: The most advanced Diesel automobile sold in America.

©Mercedes-Benz 1974

© 1974 SCIENTIFIC AMERICAN, INC Nor does he tell us that in 18 years Dur articles with tactics redolent of the Ro ham was not freely adopted in any other man gladiator circus. Federal court jurisdiction, nor does he offer his colleagues' reasons for this re JACQUES M. QUEN, M.D. jection. It is not surprising that some consider Department of Psychiatry Judge Bazelon's construction of the law The New York Hospital naIve when he says, regarding M'Nagh Cornell Medical Center ten, "according to this holding of a Brit New York ish court in 1843 ...." After the M'Nagh ten trial was completed the House of Lords asked the 15 judges of the Queen's Sirs: Bench to clarify England's law regard It would be pointless to use this space ing criminal insanity by answering five to respond to Dr. Quen's ad hominem questions. The judges, with one dissent, arguments or to engage in a controversy did this in conference, with none of the over the details of individual cases. For legal trappings or judicial aids of court example, he thinks it important that the process. They were analogous to a Con case of Rouse v. Cameron involved a gressional committee, advisory or inves person who was heavily armed when ar tigative, but were not empowered to rested and who was unwilling to be treat make legally binding decisions. Their ed. Those facts relate only to the particu answers, the M'Naghten rules, formu lar decision to be made in Rouse: What lated in an atmosphere of political and constitutes adequate psychiatric treat civil turbulence, ignored and obliterated ment under a statute that gives a right to some liberal elements in the common law such treatment? But the question I raised of England of that time. in the article was: How should courts go Judge Bazelon speaks righteously of about deciding issues involVing psychi the responsibility to accord due process atric expertise? Whether the treatment to all. However, he quotes some anon offered to Rouse was in fact adequate to ymous "leading forensic psychiatrist" his peculiar needs is entirely irrelevant damning a hospital staff conference that to my question. decided a controversial diagnosis by a Dr. Quen does make one observation, five-four decision as a "star-chamber however, that deserves further attention. proceeding." This conference released He joins many others, including myself, StraIght talk the individual for public trial, where who have suggested that the adversary psychiatrist witnesses for the defense process has serious inadequacies as a about a JtyIUJ' could challenge the staff diagnosis open method for resolving controversies. (Dr. ly. A major defining characteristic of the Quen and other readers may wish to You can still hear some audiophiles refer to the star-chamber proceeding is the use of refer to articles I have published in record stylus as ••• "the needle." The fact is that anonymous witnesses, such as Judge the legal literature taking the adversary the stylus of today bears no more resemblance to Bazelon's, who cannot be questioned process to task for its shortcomings both a needle than it does to a ten·penny nail. In fact, about testimony, personal involvement, in theory and in practice. For example, a Shure stylus is probably the most skillfully as sembled, critically important and carefully tested credibility or even qualifications as a "The Defective Assistance of Counsel, component in any high fidelity system. It must "leading forensic psychiatrist." Does University of Cincinnati Law Review, maintain flawless contact with the undulating Judge Bazelon allow this kind of evi Volume 42, page 1, 1973; "New Gods walls of the record groove -at the whlsper dence in his court? for Old: 'Efficient'Courts in a Demo weight tracking forces required to preservethe fidelity of your records. We put everything we Judge Bazelon may have convinced cratic Society," New York University know into Shure Stereo Dynetic Stylus Assemblies some readers of Scientific American that Law Review, Volume 46, page 653, -and we tell all about it in an informative book psychiatrists obstruct legal process and 1971.) There is a continuing inquiry let. For your copy, write: are responsible for the failure of Dur within the legal profession about these ham. His article suggests to me that his defects, and various improvements have Shure Brothers Inc. 222 Hartrey Ave., Evanston, III. 60204 scholarship and his credibility are de been tried. To date no model has ap In Canada: A. C. Simmonds & Sons Limited ficient and not what should be expected peared that does not entail even greater from a presiding judge sitting so close to defects. But the inquiry has revealed n the Supreme Court. I do not know why weaknesses and helped to remedy some he used half-truths and anonymous testi of them, or at least to mitigate their mony. Perhaps Judge Bazelon does. effects. The problems of legal insanity should Important and interesting as a discus concern all citizens. The solutions re sion of the role of lawyers and judges in quire thoughtful consideration of all con the adversary process may be, this point tributing factors, not shortsighted scape is only tangential to an article titled goating. Lawyers, psychiatrists and "Psychiatrists and the Adversary Proc judges are in need of better education ess" (emphasis added). Nowhere does and understanding in this area. I suggest Dr. Quen attempt to answer the ques that the method of the university seminar tions I raised about the limitations of is better suited to this purpose than are psychiatriC expertise. Instead he con- 10

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© 1974 SCIENTIFIC AMERICAN, INC trives to confuse the issue by attacking not what I said about psychiatrists but rather what I did not say about the in adequacies of lawyers and judges. Dr. Quen's only positive suggestion, • relegated to the final sentence and given no explication, is the use of "the univer sity seminar" to advance education and understanding. If he means to say that we need ongoing inquiry to explore new approaches, I quite agree. To be sure, I consider this article, as well as many of my previous writings and opinions, to be a part of that process. Articles and court opinions are never meant to take the place of discussions (in universities or CANSO SPREADS 800 GALLONS OF WATER AT A TIME , SCOOPED FROM NEARBY LAKES IN HIGH·SPEEDTAXI RUNS. elsewhere), but they are clearly relevant to any discussion of these issues. QUESTAR PHOTOGRAPHS THE FIREFIGHTERS But if articles are no substitute for seminars, neither are seminars a substi Questar owner, The Reverend James Keyworth, sent us a fabulous collection of photographs tute for court decisions. Dr. Quen seems of forest·fire fighters taken with his Questar at the NORAD Radar Site in Quebec. What had started as a brush fire was fanned by a steady 30 mph breeze that sent flames licking up the to be implying that the university semi mountain toward the radomes on top. Airborne help quickly converged on the scene and nar (or, more broadly, purely scientific there are many excellent shots of the planes in action, 2 of which are shown here water· research and debate) is a better way bombing the blaze. The film was Tri·X, exposed at ASA 1200. Focusing the Questar was than the adversary process to reach con tricky, Keyworth says, what with the planes moving away from him at 1 SO feet per second, I clusions about psychiatric questions in but in every case the picture is sharp and clear with great depth of field. "Ever since acquired my Questar it has been my gool to secure interesting stop.action aviation photographs," he the courtrooms. Certainly if behavioral says. We have the whole collection with his story in a leaflet for those who would like it. Just scientists reach a consensus about a par drop us a card.

ticular problem, the decisions required AT LEFT. A MAJOR CONFLAGRATION THREATENS RADOMES ON MOUNTAIN (SHOWN BETWEEN of courts and juries are simplified. If such BLOWING FLAGS) 3·1;2 MILES AWAY. QUESTAR IN FOREGROUND.RIGHT, FIRE NOW UNDER CONTROL. decisions were purely technical matters, perhaps they could be left to the "ex perts" to resolve. But courts must decide controversies as they arise in individual cases, long be fore the experts may reach consensus. And these are not merely technical deci sions, neatly isolated from questions of social policy and community values. The law does not ask simply: "Was the criminal defendant insane when he killed his victim?" It asks instead: "Was the defendant insane in such a way that he should not be held criminally respon For a complete description of Questar, 'he world's finest, most versatile telescope wi,h its many' sible?" The first question might be called special applications in research and industry, be sure to send for the Ques'ar boolcle, contain· purely technical except that there is no ing 150 pho,ographs by Questar owners talcen with the 3·1 (2 and Seven. Send $1 to cover consensus about insanity in the psychi moiling costs on this continen,. By air '0 Sou,h America, $2.50; Europe and North Africo, $3; all other areas, $3.50. 01974 Qu estar Corporation atric community. But the second ques tion clearly demands that social and mor al judgments be taken into account in resolving the scientific controversy. At QUESTAR that point the obstacles to resolution by Box F20, New Hope, Pennsylvania 18938 a neutral expert become insurmountable Questar resolves detail of Gouvernement Du Quebec plane traveling at 100 mph. Note name and the question becomes one for judges visible in the shadow and pilot in cockpit. Antennae wires are to beseen on the print. and juries as representatives of the com munity. That brings us back to square one: In the absence of expert consensus, how are courts to make the decisions that so ciety demands?

DAVID L. BAZELON

Chief Judge United States Court of Appeals Washington

How fast a drink of Scotch whiJ;ky over rocks loses its flavor depends on the proof of the Scotch and the richness of its blend. These two factors are optilnized for "on the rocks" Scotch drinkers in 90-Proof Fam�ous Grouse, a venerable old brand from Scotland only recently introduced to America.

by Allen Mac Kenzie

n countries where Scotch has been "the ideal sip." From then on, the Scotch origins of the malts, aging methods -these consumed for centuries, ice and whisky drinker's enjoyment typically runs down are also important factors determining Irarely mingle. But on this side of the hill, as the drink loses its freshness. the relative richness of Scotch flavor. Atlantic, the picture is quite different. The makers of Famo us Grouse While a small percentage of American Matthew Gloag & Son of Perth, Scotland Scotch drinkers take it neat, better than -have been producing Scotch in the same 35% drink it "on the rocks." The rest of us family for six generations. And they have add varying amounts of water, club soda, performed their most noble feat in the rich etcetera. And ice. Always plenty of ice blend they created for Famous Grouse -the great American drink requisite. Scotch. Its flavor-so remarkable at the It would seem then that the American outset -holds firmly to its character dur Scotch devotee, particularly our on-the ing prolonged contact with ice. rocks fancier, has a right to raise a serious Knowledge of Scotch, however, cannot question: Is the Scotch I drink ideally be indefinitely pursued in the abstract. suited to enjoyment over ice? Your learning process must ultimately in clude a leisurely sip of Famous Grouse on Pursuing a Perfect Proof the rocks. For Scotch drinking is one of While there is no way to preserve that Let's turn our attention first to the proof at those pleasures enjoyed most, not in the fresh Scotch flavor indefinitely, we submit which Scotch whisky is bottled. Consider pursuit, but in the conquest. Scotland's that you can sustain the freshness sub the hypothesis that there is indeed a better greatest bard, Robert Burns, said it best: stantially longer with 90-Proof Famous proof for on·the-rocks Scotch drinking than "Gie me a spark 0' Nature's fire, Grouse. If you have never heard of this that of the brand you currently favor. That's a' the learning I desire." brand, we are not surprised. It is a well """'-"""---""!"III Practically every Scotch sold in this established name in Scotland, but only country is bottled at 80, 86, or 86.8 Proof. recently introduced to America. So far as So at the instant you pour Scotch over ice, we know, Famous Grouse is the only Scotch it contains between 40% and 43.4% alco now available in this country at 90 Proof. hol by volume. (Proof is double the per cen tage of alcohol. ) The chilling effect of A Revealing Experiment the ice is accompanied by dilution. And when your drink has been properly cooled To demonstrate the merits of a slightly -in 30 seconds to a minute-you achieve higher proof, we performed a simple exper what one Scotch connoisseur refers to as iment: 50 millilitres of Scotch (about 1.7 ounces) was chilled with 100 cc of ice. The ensuing dilutions at 80, 86.8 and 90 Proof are charted in the graph at left. ad' You'll notice that after 15 minutes on the rocks, the proof of Famous Grouse is diluted to a level which occurs after 12Y,

60 minutes when the Scotch is 86.8 Proof, ' �� r� and after 9 minutes when it is 80 Proof. sd' ,..:;:- In essence, the Famous Grouse brand has �� remained about 2'/, minutes fresher than r----::::: - - 86.8-Proof Scotch (Interval A on graph), - 6 minutes fresher than 80-Proof Scotch a 30 (Interval B). If you "nurse" a drink beyond o� 15 minutes, the advantages of 90 Proof MINUTES 5 10 15 20 25 30 Scotch are even more pronounced. DILUTION BY ICE OF SCOTCH AT Proof. of course, is not the only influ THREE DIFFERENT PROOFS 172°n ence on the flavor of a blended Scotch. 90 PROOF, BLENDED SCOTCH WHISKY BOTTLED IN SCOTLAND _ 80 Proof _ 86.8 Proof _ 90 Proof The proportion of malt to grain whiskies, IMPORTED BY AUSTIN, NICHOLS & co. LAWRENCEBURG, KY.

© 1974 SCIENTIFIC AMERICAN, INC capacity of from 300,000 to 750,000 from which the energy is reHected and 50 AND 100 horsepower." concentrated into the form of a beam." "The long, grueling flightof the Army . "Cellophane is a perfectly transparent aviators in their attempt to circumnavi substance that can be made in extremely YEARS GO gate the globe by airplane is nearly com thin sheets. All of it hitherto has come pleted. Of the three airplanes that de from France, but now announcement has parted Seattle on the firststage of the been made that an American company Hight for Alaska, the Pacific isles and has devised a process for making cello Japan, two have survived the journey as phane here. The process consists in tak far as Iceland, where the Hiers are now ing pure wood pulp and treating it first waiting to attempt the hop to Greenland. with caustic soda and then with carbon When they come safely through this disulphate. The product thus obtained is OCTOBER, 1924: "For many years it hazard, they will surely complete their forced through a slit-like aperture into a has been realized that a star must grow circumnavigation." coagulation bath, where it solidifies into hotter as it contracts, but this contraction a solid, transparent mass." was thought to be limited by the density "Biochemistry is undoubtedly one of at which the atoms of the gas were the most fascinating, but at the same packed so closely together that little or time one of the most complicated, no free space remained between them. A branches of chemistry. Through the recent paper by Professor Eddington study of fermentation, however, science suggests that the contraction may go has reached a clearer understanding of OCTOBER, 1874: "New York has a much further than had been thought. In biochemical processes. For many cen death rate such as few cities in Christen side a star the temperature must be mea turies it was known that in the presence dom can equal. The appalling mortality sured in millions of degrees, Eddington of certain organic substances, which of the past summer, especially among points out. Under these conditions all the were called ferments, chemical changes children, has given rise to a great amount outer electrons of atoms would be in organic matter took place. The fer of sorrow and indignation, and not a lit knocked loose and the remaining residue ments were divided into ferments of cel tle criticism of the medical and police would be very much smaller. From in lular structure and ferments without cel authorities. That much might have been vestigations of X rays the diameters of lular structure, or enzymes. Some of the done to improve the health of the city by such atomic residues can be estimated, greatest chemists of the 19th century, sanitary measures there is no doubt; the and Eddington concludes that no influ however, were firm in their belief that great source of disease and death in the ence of their close packing would be per there is no difference between the kinds city, however, is the tenement-house sys ceptible until the density became at least of substances. The proof of this theory tem, whereby families are massed by the 10,000 times that of water. One great ad was provided by Eduard Buchner when hundreds in huge barracks, destitute of vantage of the new theory is that it ex he discovered that the reactions by light, ventilation and the means of keep plains such a star as the companion of which sugar is split up into alcohol and ing clean. Only by the dispersion of Sirius, which is very much fainter than carbon dioxide take place in the absence the tenement-house population can the the sun but nearly as massive and a good of living ferment cells. Recent researches death rate be reduced to reasonable lim deal hotter on the surface. If it is as have established that the ferments are its. There is no way by which such a de bright per square mile as this implies, it merely catalytic agents. Furthermore, sU'able result can be effected humanely would be only three times the diameter they do not confine their activity to the save by providing means for carrying the of the earth and 50,000 times as dense breaking down of complicated chemical poorer working people to and from coun as water. This last deduction has always combinations into simpler ones: they are try homes more rapidly and cheaply than been supposed to be absurd. If Edding also capable of building up more com is possible with surface roads." ton shows that it is not, he will have plex compounds from simpler ones. In done us all a service." one respect the ferments do differ from "The spectroscope has explored the the majority of other catalytic agents. far-off space of heaven. The light of hun "The superpower scheme is planned to Each ferment is adapted to act as cata dreds of stars has been analyzed, and do the same thing with electric power lyst in one particular set of reactions nebulae, scarcely visible, have had the that the engineer did more than 100 only, in some cases discriminating be quality of their radiations revealed by its years ago with water-gather it in a few tween sugars that differ from one an aid. The light, in some cases very feeble , great centralized power stations and other only by minute differences in mo with which a number of stars shine gives 'pipe' it to the user. The subcommittee lecular structure." a spectrum with dark lines like the solar of the Northeastern Superpower Com spectrum. This fact proves that the con mittee, under Secretary Hoover, has re "It has been found possible to con stitution of these stars is like that of our ported in favor of building large cen centrate radio energy more or less in one sun. Aldebaran sends us records not only tralized electric plants and feeding the direction by the use of wave lengths of hydrogen, magnesium and calcium, output into interconnected transmission much shorter than those used in ordinary which abound in solar light, but also of lines for distribution to every kind of commercial broadcasting. Marconi and metals such as tellurium, antimony and power user. The vast electric power res Franklin have developed a system in mercury. Matter is everywhere the same. ervoir thus formed will serve the section which the wave length is six to 10 me We meet the hydrogen of water in the of the country extending east of the Al ters. The aerial is very small, consisting sun, in Sirius and in the nebulae. Every leghenies from Maine to Maryland. To of a short wire with the transmitter in where matter moves, everywhere it vi obtain the maximum economy the power serted at the center. This is placed ver brates, and tllese movements appear to will be developed in large plants with a tically and is at the focus of a parabola, be inseparable from the atoms."

© 1974 SCIENTIFIC AMERICAN, INC abroad in Denmark, Switzerland and, 100 most recently, at the Zoological Institute THE AUTHORS at the University of Tokyo, as a Guggen Shares of heim Fellow. During my stay in Den mark I met, wooed and won my wife, Willcox & Gibbs AL VA MYRDAL ("The International who is a scientist in her own right, pur Control of Disarmament") is a Swedish suing a full-time career. With two biolo f expert on disarmament who has served gists in the family and two active sons, 2 OZS.OIVS. as the cabinet minister in charge of dis we keep rather busy. I findtime for un armament affairs and as her country's strenuous walks in the Berkeley hills and chief delegate at the international dis for reasonably frequent trips to theaters, armament conference in Geneva. She is restaurants, shops and museums of all ; =c � I� . the wife of the well-known author and kinds. These interests in city amenities � ; � �� "' �� Q= "' GltDscholar Gunnar Myrdal. In addition to are perhaps what one would expect of a her official work on disarmament she is native New Yorker, but I also appreciate They cost about the same a member of the Swedish parliament and the beautiful country that surrounds the but your investment in Willcox & was Swedish ambassador to India. She Bay area and the open attitudes that one Gibbs common stock should was graduated from the University of finds here." pay you $10 00 this year... that's Stockholm in 1924, obtaining her mas $10 00 more than gold pays. ter's degree at the University of Uppsala DAVID R. SAFRANY ("Nitrogen in 1934 and her Ph.D. from the Univer Fixation") is president and research di Want more information? sity of Leeds in 1962. Among her many rector of the Aerokinetics Corporation, activities in Sweden and the U.S. was which he founded; its business is energy

Wnte or call Mr A 0 P leuber1 Presdenl. WIIIeO)!; & GIbbS. Inc the Swedish Training College for Pre conversion. He was graduated from 1040 Avenue 01 the Amencas New York New York 10018 1959 Telephone (212) 565 7900 (AMEX Symbol WG) school Teachers, which she founded in Rensselaer Polytechnic Institute in 1936 and served as director from 1936 and obtained his Ph.D. (in physical to 1948. chemistry) there in 1964. After an addi tional year there as a research associate address JOSEPH S. MILLER ("The Structure he did research work with various cor city of Emission Nebulas") is associate pro porations until he set up his own firm in

state ZiP codE! fessor of astronomy at the University of 1972. Safrany describes himself as a con California at Santa Cruz and associate servationist and an admirer of the Cali astronomer at the Lick Observatory. He fornia coast, which he rides along on a did his undergraduate work at the Uni motorcycle and flies over in an airplane versity of California at Los Angeles and that he pilots himself. received his Ph.D. from the University of Wisconsin. "I findthat astronomy JAMES MARSTON FITCH, JOHN consumes most of my waking hours," he TEMPLER and PAUL CORCORAN writes, "and a good many generally re ("The Dimensions of Stairs") are re served for sleeping, but I have managed spectively professor of architecture at to pursue a few outside interests. One of Columbia University, associate professor them is wine: for the past four years I of architecture at the Georgia Institute have taught a course in enology at of Technology and associate professor of Crown College-a course that stresses rehabilitation medicine at the Boston the scientific aspects of viniculture as University School of Medicine. Fitch is well as appreciation of the end product. at Columbia's Graduate School of Archi I also enjoy bicycling and have spent tecture and Planning, where among many weekends exploring back roads in other things he directs what he describes the Santa Cruz Mountains." as "a program in the retrieval and re cycling of historic sites and structures." PETER SATIR ("How Cilia Move") is Templer, who was born in England, has professor in the department of physi a bachelor's degree in architecture from ology-anatomy at the University of Cali the University of Pretoria and the gradu fornia at Berkeley and director of the ate diploma in town planning from the Electron Microscope Laboratory. "I was University of the Witwatersrand. His graduated from Rockefeller University master's degree and Ph.D. are from Co in 1961," he writes, "shortly after my lumbia. Corcoran was graduated from Please send me ___ set(s) of the special first article appeared in Scientific Amer Georgetown University and received his limited offer of the 12 piece Art Miniature set @ $9.95 per set and/or ___4 piece sets ican ["Cilia," February, 1961]. I spent M.D. there in 1959. at $3.95 per set. Total enclosed $ ____ most of the next six years at the Univer Name sity of Chicago in zoology and in biology JURGEN NICOLAI ("Mimicry in

I Address at the college, rising through the junior Parasitic Birds") is at the Max Planck I I ranks of the academic ladder. In 1967 I Institute for Behavioral Physiology in : City State Zip received my first appointment at Berke Seewiesen, where for many years he : MAIL ORDERS TO: IMG Products, Inc. ley. I have had the good fortune to spend worked with Konrad Lorenz. He is now I 27 E. 39th street, New York, N.Y. 10016. SA-2 L ______several periods in various laboratories in the department of ethology and serves

The Sinclair Scientific is the only keyboard has only four function keys. pocket calculator that offers scientific All of which provide "triple-action" by capacity at a truly affordable price. changing from standard to upper or lower case mode. And look how much you get: 8.EiEi29 -0 I log and anti-log (base 10) Old hands at small miracles, sin and arcsin Sinclair has been an innovator in cos and arccos calculator miniaturization right from tan and arctan the start. automatic squaring In the last two years Sinclair brought automatic doubling 1rad 57·2958' to America the Sinclair Executive and xY, including square and Inl0 2·30259 Eiin�lair Executive Memory -the world's other roots e 2·71828 Scientific 1T 3·14159 thinnest, lightest calculators -as well four basic arithmetic as the Cambridge. functions The Sinclair Scientific is backed by plus scientific notation an unconditional one-year replacement (10-99 to 10+99). warranty. All for an incredible $69.95. Sinclair also maintains a service-by What makes a scientific return mail operation in the U. S. (and calculator scientific? everywhere else in the world) to handle To be a really valuable tool for any product problems. engineers, scientists, technicians and How to get your students, a calculator must provide all Sinclair Scientific, of the above. The Sinclair Scientific may be Clearly, a scientific calculator ordered by phone or mail. And you may without scientific notation severely charge it to your American Express, limits the size of numbers with which Diners Club, Master Charge or you can work easily. BankAmericard account. And scientific notation without If you're not completely satisfied, transcendental functions is little more you may return the unit within 2 weeks than window dressing on an arithmetic of receipt for prompt refund. calculator. Just fill in the coupon and mail it to: Granted, there are companies other Sinclair Radionics, Inc., 375 Park Avenue, than Sinclair offering excellent units What makes the Sinclair New York 10022. Or call (800) 223-5764, with all the essential ingredients. Scientific so inexpensive? toll free. But they sell at much higher prices. Two important technological What's more, the Sinclair Scientific breakthroughs. isn't just portable. It's pocketable. First, the British-built Sinclair Eiinl::lair Less than 3/4-inch thin. And 33,4- Scientific has a single integrated circuit. ounces light. It's the world's thinnest, Engineered by Sinclair. SCIENTIFIC lightest scientific calculator. Second, Sinclair's exclusive The logical choice. r------, Specifications ORDER FORM For credit card phone orders call (800) 223-5764, toll free. (New York residents call (212) 688-6623.) Functions: Logic: I To: Sinclair Radionics, Inc. 375 Park Avenue, New York, New York 10022 4 arithmetic Reverse Polish, with I 2 logarithmic post-fixed operators Please send me Sinclair 6 trigonometric for full flow chain I Scientific(s) at $69.95 (plus SI.50 per unit, shipping and handling) including balleries, I Keyboard: calculations. Signature______carrying case, instruction booklet and war- 18 key format with Power Source: I I 4 "triple-action" Ballery operated with ranty. New York residents add sales tax.) Name ______function keys using 4 inexpensive AAA I o Enclosed is my check for ______I standard, upper and penlight balleries, o Please charge my credit card account. Company.______lower case operation. providing over 25 Credit Card Address ______Display: hours of use. I I 5-digit mantissa Size: Account No. City______2-digit exponent 4%" high; I I (both signable) 2"wide; thick. 11116" Expires State ______Zip Code___ Exponent: Weight: I I 200-decade range, 3311 oz. Master Charge Code # (4 digitsl 16C from 10 -99 to Warranty: -- I year. -- 10 + 99 lIn ------the United Kingdom: Sinclair Radionics, Ltd.,--- London Road, St.- Ives, Huntingdonshire- . - J In Germany: Sinclair Elektronik GmbH., 8012 Ollobrunn (Munchen), Rosenheimer Landstrasse 39.

© 1974 SCIENTIFIC AMERICAN, INC just like a completely free checking ac also as a university lecturer at the U ni New block of count with no minimum balance re versity of Munich. Nicolai studied zool quired. ogy, botany and anthropology at the "U.S.A." Bank Accounts The bank is in the quarter-billion dollar class with exceptional reserves University of Mainz from 1949 to 1954, to be opened and F.D.I.C. insurance. All transactions receiving his doctorate there in 1954. In are by postage-free mail. to the public A bank spokesman reports that peo pursuit of his interest in birds he has ple with "United Security Accounts" made five research trips to Africa, visit Announce expansion of only bank plan earn as much as $100, $500 or more In U.S. that allows both checks and extra interest every year even though ing Tanzania, Kenya, Uganda, Cam top interest at same time they can still write checks up to their eroons and Nigeria. full balance. He said accountholders Citizens Bank & Trust Company in enjoy the convenience of one, confiden suburban Chicago has announced that tial bank account that does the work of EMILIO BIZZI ("The Coordination a new block of its unique "United two separate savings and checking ac Security Accounts" is being released to counts. of Eye-Head Movements") is professor the public. Although "U.S.A." accounts are held of neurophysiology in the department of These are the only nationwide bank by 80,000 depositors throughout the psychology at the Massachusetts Insti accounts in the United States that pay United States and in many foreign coun maximum savings rate interest on tries, new accounts have only been tute of Technology. "I was born in a vaiJable at limited intervals, mainly to money that would ordinarily be earning Rome," he writes, "where, after laboring nothing in a.checking account for imme persons recommended by present ac diate access. Accountholders can write countholders. Now the bank says it will through the required years of Latin and free checks on credit against the entire release a block of new accounts for Ancient Greek, I moved on to the Uni account while the interest is compounded applicants without recommendation. daily on the remaining balance. During this limited applica tion period, versity of Rome's Medical School, gradu Like a free checking account that anyone interested is invited to send, ating in 1958. Ironically, while interning pays highest savings account in without obligation, for a free booklet terest. There are no check or service describing the special advantages of at the medieval hospital of the city of charges, and because of a free repay these accounts. The convenient coupon Siena I became attracted to modern neu ment period, the account can be used below should be sent without delay. rophysiology. This interest led me to the r------FREE BOOKLET Institute of Physiology at the University I Howard S. Hadley, U.S.A. Director Citizens Bank & Trust Co., Dept. SA-25 of Pis a, where I received my neurophysi III. 60666 I (Park Ridge) Chicago, ological training. Thereafter I pursued Please mail me my free booklet with full information on I how I can use a "United Security Account" like a free my career in the U.S. at vVashingtol1 I checking account that pays highest savings account interest. University, the National Institutes of I NAME Health and M.LT. I have no major'in I ADDRESS terests outside my work, although I play I CITY STATE ZIP tennis as often as possible and follow closely contemporary literature and mu sic."

MICHAEL H. JAMESON ("The Ex cavation of a Drowned Greek Temple") He said: is professor of classical studies at the University of Pennsylvania. Born of We think hot American parents in London, he spent arrived so things should much of his childhood in Peking, where quickly this be hot. his father was a college teacher. He traces his interest in archaeology and mormng, my antiquity to that time. He acquired his eggs Benedict bachelor's degree and his Ph.D. (both in were still hot. Greek) at the University of Chicago, spent a year at the American School of We said: Classical Studies in Athens and then He said: taught at the University of Missouri for Like my bath Ah, the heated four years before joining the Pennsyl towel? towel rack ...just vania faculty in 1954. From 1966 to part of our service. 1968 he was dean of the Graduate School of Arts and Sciences at Pennsyl The Stanford Court Hotel. vania. Since 1968 he has been director Young, sentimental, graceful and human. of the university's Center for Ancient History. The work Jameson describes has An original, just like San Francisco. been conducted for the American School of Classical Studies in Athens by the G((fl;a University of Pennsylvania and Indiana University with support from the Na S!ANFO�COU� tional Endowment for the Humanities, the Ford Foundation and the National on 8an'Frnndsco's

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The HP 70: a new business problem in any order and change any number in the problem without having to re-enter the other calculator you won't outgrow. numbers-a nice convenience. The HP-70 also has two addressable memories A little over a year ago, we introduced the and a four-memory operational stack. This stack, HP-80, the first pocket-sized calculator for time plus the non-algebraic computer logic we use and-money management. Although we designed in all our pocket calculators, lets you solve all it expressly for the financial specialist, it wasn't problems in the same consistent way, even when long before non-specialists were buying it by the they include serial, chain, or mixed calculations. thousands, simply because the HP-80 served the (You'll find more information on our non needs of business far better than any existing algebraic approach across the page.) You never pocket-sized calculator. Out of this realization have to jot down and re-enter intermediate results came the new HP-70. obtained during chain calculations because the Designed to solve the general time-and-money operational stack stores them for you and brings problems of the businessman rather than the them back to the working register-automatically. special calculations of the financial professional, Each of the HP-70's two addressable memories the HP-70 is easier to use than its financial coun (the K and M keys) lets you store any number that terpart. Its keyboard is simpler. Yet the HP-70 you might want to use later in a lengthy calcula retains the row of five financial keys found on the tion or repeatedly in a series of calculations. HP-80, pre-programmed to solve more than 100 Since you can use one of these registers (M) as an time-and-money problems. Problems such as accumulator, you can keep two running totals at compound interest, effective return on invest the same time--one in the stack and one with M +. ment, declining balance depreciation, mortgage As you discover more and more ways to put payments, finance charges, future value of an your HP-70 to work, its exceptional calculating annuity, etc. All you do is press the keys. The power will give you capability you won't out ponderous equations and cumbersome tables are grow. And the quality and care of its manufacture stored electronically in the HP-70. mean that it will be fully operational when you To make these powerful financial keys really need it. The $275 * price includes rechargeable easy to use, we gave each its own memory bank. batteries, AC adapter and battery charger, soft Now you can enter the numbers of a financial case, owner's handbook, and reference guide.

© 1974 SCIENTIFIC AMERICAN, INC HP pocket-sized calculators of time figuring out how to put them into an al gebraic calculator. "A plus B times C minus D give you answers you can trust. divided by E equals" won't do it. (Why we chose to be different.) You find you must write down intermediate answers to re-enter later. You may work your Most pocket-sized calculators have an = key, way through a long equation and see an answer and you can pick up one you've never seen be you know is wrong. Where did you goof? fore and solve a simple equation by entering Or you may get a wrong answer and think it's values the way they're written and pressing = to right. Disaster. see your answer. Our non-algebraic approach not only makes it Pick up one of our pocket-sized machines and unnecessary for you to write and re-enter inter you'll hunt in vain for the = key. Instead you'll mediate results, but gives you the continuous see one that says ENTER and you'll wonder what feedback you need to avoid ending up with a to do with it. wrong answer. To find out, you'll have to look in the Operating It's an approach we first adapted and applied Manual. When you do, you may think, "Why some years ago, using an unambiguous, paren did they go this route when they could have kept theses-free language developed by the Polish it simple?" mathematician Jan Lukasiewicz. But as you work the examples in the manual Before you invest in a pocket-sized calculator, and practice with your own problems, you'll you should look beyond its ability to solve simple find yourself thinking, "This is very easy, and problems in the most obvious way. To under I'm getting answers I can really trust." stand more fully the difference between our Easy because you always enter your data the approach and the algebraic one, return the cou same way-from left to right, the way you read pon for a copy of the booklet ENTER VS. =. You owe an equation, but without having to keep track it to yourself to read it. We will also send you of parentheses and brackets. information on our pocket-sized calculators: Trust because you see the result of each inter the HP-35 electronic slide rule ($225*), the HP-45 mediate calculation displayed as you perform it, advanced scientific calculator ($325*), the HP-65 and you can check your progress and correct programmable computer calculator ($795*), the errors as you go. You can also go back and review HP-70 business calculator ($275*). and the HP-80 stored numbers at any time. financial calculator ($395*). When we started out to design a small, power ful scientific calculator several years ago, we assumed it would have an = key. It did, in the For more information on these products write breadboard stage. to us. Hewlett-Packard, 151)5 Page Mill Road, But along the way from breadboard to proto Palo Alto, California 94304. type, our designers realized that there was a bet ter method which got around some of the severe -Domestic USA prices only. 00434

...... limitations inherent in the "algebraic" approach. . . . . ' These limitations start showing up as problems Mail to: Hewlett-Packard, 1505 Page Mill Road, Palo Alto, CA 94304 . • get more complicated and you have to spend a lot

Please send me the ENTER VS = booklet, together with information on HP pocket·sized calculators.

Name Title HEWLETT iI PACKARD Company

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Continental Oil Company (conoco)

Established 1845 AM E RI CAN October 1974 Volume 231 Number 4

The International Control of Disarmament

7he widely acknowledged need for a separate United Nations agency responsible for verifying and controlling disarmament agreements is intensifiedby the current impasse In bilateral "summit" talks

by Alva Myrdal

wo recent deve lopments-the fail tions have so often been raised against some of the reasoning behind this pro Ture of the latest round of bilateral agreements on arms limitation or genu posal. "summit" meetings between the ine disarmament on grounds of the dif The value of any agreement on disa r U.S. and the U.S.S.R. to make any sig ficulty or the alleged impossibility of con mament or the regulation of armaments nificant progress toward the immediate trolling their implementation, the prob depends not only on how large a part of goal of strategic-arms limitation (let lem of control and verificationmust be the community of nations subscribes to it alone toward the ultimate goal of nu tackled in a new and dynamic way. but also on mutual confidence that it will clear disarmament) and the announce be duly upheld. Ultimately such eonfi ment by India that it had become the have therefore come to the conclusion denee depends on the trustworthiness of sixth nation to successfully test a nuclear I that there is one practical measure the nations that are parties to the agrec explosive-serve to emphasize the urgent that could serve to bind together and ment. All properly share in the eoncern need for renewed international efforts to facilitate all disarmament efforts.That is that they should be able to rely on the end the continuing waste and insecurity to create a new UN agency eharged with other parties to fulfill their obligations. of the arms race. As Sweden's delegate the collection and dissemination of in The overriding assumption must be that to the Political Committee of the United formation regarding the fulfillment by any government that has negotiated a Nations and to the ongoing UN disarma the nations of the obligations they incur disarmament (or nonarmament) agrec ment conference at Geneva from its be under disarmament agreements and re ment, and that during the preparatory ginning in 1962 until my retirement last garding ongoin g ehan ges in national period has worked to get the agreement year, I have been in a position to witness armaments. Such an agency would begin tailored as mueh to its wishes as mutual the ebb and flowof the arms-regulation its work modestly, depending on infor ity allows, will enter as a party to the proposals that have been put forward at mation available from national sources, agreement with no intention of breaking various times by various nations. Out of but ultimately it would stand ready to it or of cheating. this experience I have distilled a few accept control functions. It might even The historical record speaks for the general observations about how (and become a repository and publisher of validity of this assumption. It is doubt how not) to negotiate an effective arms pertinent satellite-surveillanee data. I am ful, in fact, that there has ever been an agreement. eonvinced that this approach to the in instance of a clandestine violation in the First and foremost it should not be ternationalization of knowledge about arms field. Some Americans have eharged tolerated that the two superpowers ex arms and disarmament would seeure the that the U.S.S.R. violated the nuclear ercise a world hegemony based largely foundations for the mutual eonfidenee test moratorium that prevailed at the end on their incessant arms race and at the among nations on whieh thc negotiation of the 1950's. In the first plaee there same time play an insincere game of and observanee of signifi cant disarma could not have been any such violation disarmament at the negotiating tables. ment agreements must in the first and beeause there had been no formal agree Moreover, in view of the fact that objec- last instanee rest. Hcre I shall set forth ment; moreover, the U.S. had already

© 1974 SCIENTIFIC AMERICAN, INC indicated its intention of resuming test to conceal than nuclear weapons. None the treaty. In arms-regulation treaties ing. In the second place the Russian test theless, the main assumption retains its there are often provisions for such with explosion was not secret. Even less was strength, namely that the political com drawal, according to the formula that a India's recent nuclear explosion a viola mitment made when entering an arms party may decide "that extraordinary tion, inasmuch as India had for 20 years agreement is the most reliable guarantee, events ...have jeopardized the supreme worked assiduously for a ban on all nu whether or not it is supported by tech interests of its country." clear-weapons testing, and when it did nical devices for detection. Concern about loyal adherence to not sign the Non-Proliferation Treaty, it If willful violations of an arms agree agreements has been surprisingly and, in led those nations that openly expressed ment should occur, they would raise my view, irrationally vociferous during reservations about the treaty's discrimi problems that would be essentially polit disarmament negotiations. It has caused natory character. ical and not technical. Collective sanc considerable attention to be paid to ques In fact, open abrogations of treaties tions could not be enforced against such tions of control and verification. The fact are rather more likely than clandestine breaches; penalties could not be meted that the matter of control is held to be ones. It is of course true, as some com out by an international organization, nor important, however, sets out the practical mentators have pointed out, that certain could punitive expeditions be put into limits of the area of agreement. There is ultramodern weapons (for example bi the field.The risk is the political one that a plethora of differing demands for con nary chemical weapons) might be easier other parties will findreasons to abrogate trol and even differentinterpretations of

RUSSIAN SPACE CENTER near Tyuratam in southern Kazakh to include the currently secret military-satellite programs of both stan appears in this U.S. satellite photograph. The photograph, sides, on the grounds that such an approach would encourage the which was made from an altitude of about 570 miles by a camera mutual confidence among nations on which the verification and aboard the first Earth Resources Technology Satellite (ERTS 1), control of disarmament agreements depend. The ultimate reposi was released by the National Aeronautics and Space Administra tory for all such arms-surveillance data would be a new United tion in 1972 following a decision to make all such nonmilitary Nations agency to be called the International Disarmament' Control satellite photographs available to the public on request, regardless Organization. The military satellites of both the U.S. and the of the possible strategic significance of the area photographed. The U.S.S.H. are of course capable of obtaining photographs with author argues that the same policy of openness should be extended much greater resolution. The comparatively poor resolution of this

© 1974 SCIENTIFIC AMERICAN, INC what control clauses in already signed collateral measures should be related to Objections might well be raised by other and ratified treaties really mean. the specific conditions, which differ from countries with regard to possible future I believe two major unresolved issues case to case, if they are to be relevant to arms agreements. are at the bottom of the confusion. One the pragmatic attitude that is now the What is conf using the issue is to a is the remaining uncertainty about what prevailing approach to disarmament ne large extent the fact that the postures the real purpose of a control system is gotiations and debates. taken by various nations are not clearly to be in relation to an arms-regulation addressed either to a situation of general agreement. I shall return to this issue. t was on the submerged reef of obfus- and complete disarmament or to one The other issue is the continued domi I cations concerning the scope of con where disarmament is less perfect. One nance of a long-standing tendency to trol that the first major postwar arms reason is probably, as I have mentioned, view the problem in terms of the control limitation effort on the part of the U.S. the lingering dominance of the idea of a deemed to be both necessary and ac and the U.S.S.R. foundered. Since the foolproof control system. This criterion ceptable in a totally disarmed world. It debate over the Baruch Plan right after has always been associated with a state was in this context that the control prob World War II the accusations have be of world affairs where nations were to lem was originally raised and discussed. come stereotyped: the U.S.S.R. wants to tally disarmed and the UN had the duty Questions about what control measures confine control to what is being dis of policing the world society. Such an are necessary and applicable to partial or armed, whereas the U.S. wants to control ambitious scheme was embedded, for ex what exists of armaments. ample, in the basi c guidelines for disar Although this is a rather quixotic feud, mament negotiations that were submit it regrettably still turns up and causes ted to the UN General Assembly in 1961 vexations at point after point. I am con and go under the name of the McCloy vinced, however, that a meeting of minds Zorin Agreed Principles. The agreement must and will occur. In their abstract states as the sixth principle: form both positions are impossi ble. In "All disarmament measures should be concrete cases both positions may well implemented from beginning to end un be abandoned, as they were in the first der such strict and effective international strategic-arms-limitation talks (SA LT I), control as would provide firm assurance or considerably modified, as they were that all parties are honoring their obliga in the nuclear-test-ban negotiations. tions. During and after the implementa In a strict sense "control of disarma tion of general and complete disarma ment" could be interpreted as being lim ment, the most thorough control should ited to monitoring the destruction of ar be exercised, the nature and extent of maments. Indeed, in the early days of such control depen ding on the require the Geneva disarmament conference ments for verification of the disarmament there was often talk of such "bonfires" of measures being carried out in each stage. bombers and other weapons. In the con To implement control over the inspec vention prohibiting the production of tion of disarmament, an international dis biological weapons the destruction of the armament organization including all par existing stock is explicitly required. Pres ties to the agreement should be created ident Nixon in 1969 made the magnani within the framework of the United Na mous gesture of promising such destruc tions. This international disarmament tion of U.S. stockpiles. The fact remains organization and its inspectors should be that international observation teams have assured unrestricted access without veto never been invited to witness the de to all places as necessary for the purpose struction of any weapons. The logical of effective verification." flaw in the demand that control be lim ited to the implementation of disarma he two contrary positions held by the ment is, of course, that in order to ap Tsuperpowers can, I surmise, be dis preciate how much has been destroyed regarded in their extreme form, when (as or eliminated one has to know what is now the rule) all relevant negotiations share of the total it represents. have moved on to the practical consid "Control of armaments retained," on eration of varied and limited disarma the other hand, is a logically more de ment measures. Problems of verification fensible proposition. In its most literal and control are considerably easier to sense-corresponding to the "bonfire" in solve in practice than in theory-either the preceding category-it would require on the political ground that enough con proof in the form of physical inspection fidence prevails or on the technological ERTS photograph is enhanced somewhat by of all facilities of any party to a treaty in ground that sufficiently reliable means the fact that it was made in winter; roads, order to ascertain that elimination or re of monitoring events in the field of inter railroads and other installations show up duction of armaments has been effected est are becoming available. Even so there clearly as black lines and spots against the will often remain margins of uncertainty light·colored background of the surround· so as to correspond to the levels agreed ing snow·covered desert. The main "cosmo· on. So far the Russians have been cate that may require a mustering of political drome," or rocket· launching complex (top gorically opposed to incorporating the will to compromise if they are not to be center), is approximately 15 miles north of right to obligatory inspections in any of used as excuses for disagreement. the railway town Tyuratam (bottom center). the treaties that have been neg otiated. The futility of demanding control pro-

© 1974 SCIENTIFIC AMERICAN, INC visions that would give 100 percent as would hold up before a judiciary au retically different angle, however, insofar surance that no violation of an arms reg thority. Thus the accused party should as it has another important function, ulation agreement would ever go unde preferably have been caught red-handed namely to prevent violations. This might tected becomes much more indisputable in the act of violation or should have left be called the before-the-fact approach. when one considers the other continuing indisputable material proof-hence the The role of control and verification would source of confusion, namely that there insistence on obligatory inspections. Only then be to establish sufficient risks of dis has not as yet been any clear analysis and if guarantees were given that such a closure that the risks as such act as a unambiguous acceptance of what is to be practically foolproof system for after-the deterrent against any nation's attempting the function of control and verification. fact verification existed, the reasoning to violate a treaty obligation. In general, interest has been focused on goes, would enough trust be engendered In relation to a treaty banning nuclear only one function: the ability to check to allow an agreement to be signed. That tests, for example, the before-the-fact ap whether or not a violation of treaty ob is still the U.S. position in regard to some proach could be effective if the parties ligations has occurred. I would call this important treaties, including a total ban were willing to accept the now very low an after-the-fact approach. The main in on nuclear-weapons tests. As a result ne margin of uncertainty that some of the terest here has been the legalistic one of gotiations on this issue have for decades lowest-yield tests might go undetected keeping the parties accountable. The evi just been treading water. and to apply to those uncertainties a dence sought should be so strong that it Control can be regarded from a theo- strategy of nonresponse. The risk would

SIGNED IN FORCE NUMBER OF PARTIES

1959 1961 ANTARCTIC PROHIBITS ALL MILITARY ACTIVITY IN ANTARCTIC AREA 17 TREATY

1963 1963 PARTIAL · NUCLEAR· PROHIBITS NUCLEAR EXPLOSIONS IN THE ATMOSPHERE, 106 TEST· BAN IN OUTER SPACE AND UNDER WATER TREATY

1967 1967 OUTER-SPACE PROHIBITS ALL MILITARY ACTIVITY IN OUTER SPACE, 71 TREATY INCLUDING THE MOON AND OTHER CELESTIAL BODIES

1967 1967 TREATY OF PROHIBITS NUCLEAR WEAPONS IN LATIN AMERICA 18 TLATELOLCO

1968 1970 NON -PROLIFERATION PROHIBITS ACQUISITION OF NUCLEAR WEAPONS BY 82 TREATY NON-NUCLEAR NATIONS

1971 1972 SEA-BED PROHIBITS EMPLACEMENT OF NUCLEAR WEAPONS AND 52 TREATY OTHER WEAPONS OF MASS DESTRUCTION ON OCEAN FLOOR OR SUBSOIL THEREOF

1972 BIOLOGICAL- PROHIBITS DEVELOPMENT. PRODUCTION AND STOCKPILING 31 WEAPONS OF BACTERIOLOGICAL AND TOXIN WEAPONS AND REQUIRES CONVENTION DESTRUCTION OF EXISTING BIOLOGICAL WEAPONS.

MULTILATERAL ARMS AGREEMENTS negotiated in recent gives the total number of parties to each treaty as of December years are listed here in chronological order, together with short 31, 1973. The convention on biological weapons had been ratified statements of their major provisions. The column at extreme right by 31 nations but was still not in force at the beginning of this year.

24 © 1974 SCIENTIFIC AMERICAN, INC strategy of nonresponse. The risk would on openness or one based on secr etive is that openness promotes all knowledge. be minimized by the factor of deterrence: ness. With respect to disarmament there Knowledge does not thrive in the dark. the calculable probability that violations is much to be said for the view that maxi This wider aspect of the ethics of access will be detected. That is obviously a far mizing the common fund of knowledge to knowledge is beyond the scope of this more effective method than to search for through a total abandonment of secrecy article. Here I wish only to emphasize 100-percent-positive proof in every sin would best serve all interests. Confidence that military secrecy is the most obnox gle suspected event whether or not the would be encouraged and deterrence ious of all attempts to conceal truth. event is a violation. would become particularly strong if all In practical terms solutions to these the nuclear powers were to participate. erification is no substitute for trust. theoretical riddles do not present great Niels Bohr suggested toward the end of VThe question of trust in a disarma difficulties. The degree of trust is always World War II that the only way to deal ment agreement remains preeminently a of the essence when an agreement is con with the problem of nuclear arms was to political problem, but verification can templated. The before-the-fact deter totally abandon the secrecy surrounding obviously contribute to trust and thus to rence approach presupposes a climate of nuclear explosions. a buttressing of international agreements. confidence, but it has the comparative Even Edward Teller, a man not given Technical means can facilitate trust even merit of motivating a willingness to take to accepting such a thorough change of outside the domain of verification,as is a firststep on somewhat shakier gro und, the ways of the world, has said that a evidenced by the "hot line" set up be since it then allows confidence to grow possible path is "a gradual and well tween the U.S. and the U.S.S.R. in 1963. gradually as it is tested by experience. planned abandonment of all secrecy con It would nonetheless be a mistake to To demand foolproof methods for after cerning technical and scientific facts." rely too much on technical contr ols. In the-fact verification is to impose an im The spread of knowledge is unavoidable the early days of disarmament negotia possible requirement. anyway, and the lack of knowledge is not tions great store was set by "strict and the main factor limiting nuclear-weapons effective international control" (as had t can be safely stated that for both production. The policy of openness must been stated in the McCloy-Zorin prin I after-the-fact verification and before be actively pursued. As Teller argues: ciples), undoubtedly because it was then the-fact deterrence a main interest is to "We should at the same time exert as hoped that general and complete disar increase the scope of knowl edge about much pressure as we possibly can on mament would emerge out of one set of what bappens to armaments as well as every nation in the world that they like decisions, in spite of the fact that the disarmament. It would be particula�ly wise permit complete freedom for the political realities were far from ripe for true, however, that the more pertinent flow of information. At the present time it. Particularly as new methods of veri knowledge was available, the more reli technical facts are subject to sec recy in fication with technical aids emerged, ance could be placed on the before-the many nations. We should try by every "control" sometimes was in danger of fact approach. means to reverse this trend toward se becoming a technical pipe dream. An ex Speaking generally, the imperative crecy. Every additional secret is an ob ample was the plan to build hun dreds of task for practical policy should be to re stacle to the free collaboration and the seismological stations around the world duce the margins of uncertainty in order eventual union of nations. A strong and for monitoring a test ban. to change the demand for control from widespread condemnation of all prac Overreliance on the inspection ap an impossible absolute requirement to tices of secrecy may in the long run have proach was pervasive throughout the pe a manageable relative require ment. In a strong effect even on those countries riod from 1958 to 1965, even in academic creased knowledge is really the link be which value this form of security most." studies of arms control and disarmament. tween the two extreme requirements con Secrecy has many negative ramifica The search went on for perfect methods cerning what to control: armaments sac tions. It cannot long preserve a purely of control, until it looked as though what rificed or armaments retained. In addi technical military monopoly. On the oth disarmament would lead to was a world tion increased knowledge serves the pur er hand, spreading exaggerated notions police state. The consoling thought is pose both of deterrence (the before-the about an adversary's superiority or one's that this approach is now virtually a thing fact risk of disclosure) and of monitoring own insufficiency tends to cause over of the past. It was based on a mixin g of (the after-the-fact search for evidence of reaction. The notorious "missile gap" of mental images: a scheme for general and violations). the early 1960's was a case in point, but complete disarmament introduced into a In this light the prospects for progress the phenomenon has a timeless ability to political situation that was totally in should become brighter. Where a fair de open up terrifying perspectives. hospitable to such brave idealism. gree of knowledge prevails, even without Among the important positive aspects The task as seen from the perspective any specific verification apparatus, the of openness is that it both increases of today is rather how to obtain increas margin of uncertainty correspondingly knowledge about ongoing developments ingly wide and reliable knowledge of ar decreases, making it less likely that a that might threaten to step up the arms maments and potential changes in their would-be violator might be tempted to race and multiplies opportunities for ver quantity and quality throughout the play a hazardous game. ification. The most advanced means of world. A reassuring openness, I would How to expand the store of knowledge observation have been by-products of hold, is the avenue to disarmament con in fields that become sensitive when dis the arms race (satellites, sonar and so trol. Even if the goal of total openness is armament measures are being negotiated forth). Regrettably these devices are now distant, to take steps in that direction is is a practical question having to do with monopolized by a few nations. Ideally clearly in line with the trend of our time, the availability of techniques. Nonethe they belong to mankind's accumulated which is toward increasing communica less, even this technological problem has fund of knowledge and should be al tion of all kinds. a political aspect. It involves the ques lowed to serve the interests of everyone's In the field of interest to arms-limita tion of what kind of world society one security. tion endeavors, however, the problems of wants to foster for the future: one based The one dictum that is generally valid verification and control have also suf-

© 1974 SCIENTIFIC AMERICAN, INC fered from being treated too much as elude the usefulness of cross-checking To date no systematic analysis has generalities. The search for verification events by employing several different been attempted to determine what dif methods must span a great diversity of approaches. Hence efforts to observe ferent disarmament measures would op problems. The choice of method must be changes in hardware can be augmented timally require of verification methods specific, depending on the type of arma not only by the examination of budget and whether some measures might not ment proscribed and the developmental figures but also by the analysis of trade make use of a common operative han stage to be verified, as well as on the statistics. For example, trade in phos dling. Instead disparate approaches to technical means at one's disposal. phorus can be analyzed for the purpose control have been taken in an unsystem This requirement for deciding on spe of monitoring the possibility of chemical atic way in the treaties and recommenda cific verification methods should not ex- weapons production. tions negotiated so far. The picture of

SIGNED IN FORCE

1963 1963 "HOT LINE" ESTABLISHES DIRECT RADIO AND TELEGRAPH COMMUNICATIONS BETWEEN U.S. AGREEMENT AND U.S.S.R. FOR USE IN EMERGENCY

1971 1971 "HOT LINE" INCREASES RELIABILITY OF ORIGINAL "HOT LINE" SYSTEM BY ADDING TWO MODERNIZATION SATELLITE-COMMUNICATIONS CIRCUITS AGREEMENT

1971 1971 NUCLEAR-ACCIDENTS INSTITUTES VARIOUS MEASURES TO REDUCE RISK OF ACCIDENTAL NUCLEAR WAR AGREEMENT BETWEEN U.S. AND U.S.S.R.

1972 1972 HIGH-SEAS PROVIDES FOR MEASURES TO HELP PREVENT DANGEROUS INCIDENTS ON OR OVER AGREEMENT THE HIGH SEAS INVOLVING SHIPS AND AIRCRAFT OF BOTH PARTIES

1972 1972 SAI,T I ABM LIMITS DEPLOYMENT OF ANTI-BALLlSTlC-MISSILE SYSTEMS TO TWO SITES IN TREATY EACH COUNTRY

1972 1972 SALT I INTERIM PROVIDES FOR FIVE-YEAR FREEZE ON AGGREGATE NUMBER OF FIXED LAND-BASED OFFENSIVE-ARMS INTERCONTINENTAL BALLISTIC MISSILES ( ICBM'S) AND SUBMARINE-LAUNCHED AGREEMENT BALLISTIC MISSILES ( SLBM'S) ON EACH SIDE

1973 1973 PROTOCOL TO PROHIBITS SIMULATED ATTACKS BY SHIPS AND AIRCRAFT OF EACH PARTY AIMED HIGH-SEAS AT NONMILITARY SHIPS OF OTHER PARTY AGREEMENT

1973 1973 NUCLEAR-WAR- INSTITUTES VARIOUS MEASURES TO HELP AVERT OUTBREAK OF NUCLEAR WAR PREVENTION IN CRISIS SITUATIONS AGREEMENT

1974 SALT II ABM LIMITS DEPLOYMENT OF ANTI- BALLISTIC-MISSILE SYSTEMS TO ONE SITE I TREATY IN EACH COUNTRY

I 1974 SALT II THRESHOLD PROHIBITS UNDERGROUND TESTS OF NUCLEAR WEAPONS WITH EXPLOSIVE YIELDS NUCLEAR-TEST-BAN GREATER THAN 150 KILOTONS I TREATY

1974 SALT II INTERIM COMMITS BOTH PARTIES TO NEGOTIATE EXTENSION OF SALT I INTERIM OFFENSIVE-ARMS OFFENSIVE-ARMS AGREEMENT THROUGH 1985 AGREEMENT

BILATERAL ARMS AGREEMENTS between the U.S. and the terns that neither side wanted anyway, with the net result that the U.S.S.R. cover mostly peripheral matters of immediate concern arms race has merely been redirected. The SALT II treaties, which only to the two "superpowers." Critics of the agreements reached in were signed in Moscow on July 3, have not yet been ratified by the the strategic-arms-limitation talks (SALT I and II) contend that the U_S. Congress and hence are not yet in force; the SALT II "thresh· bilateral approach has succeeded only in outlawing weapons sys- old" nuclear·test ban is not intended to go into effectuntil 1976.

© 1974 SCIENTIFIC AMERICAN, INC the controls attempted is therefore one of tain nations possess. More generally, in a treaty but the construction of a firm great disarray. ternational equity demands that informa basis of universal confidence through a Thus the problems of verification are tion should not be secretly held by the cumulative process of fully shared fac to a large extent concerned with the strongest powers but should be placed tual information. right choice of techniques and proce under international control. Great em dures. Such choices should, however, be phasis must be put on both increasing �l the arguments advanced in the fore- guided by the overarching aims of maxi and internationalizing knowledge. going point to the need for some in mizing trust and minimizing policing on ternational agency to which the func the one hand and gradually widening the o cement the basis for mutual trust, tions of verification and control can be appropriate knowledge through interna Tcooperation should be directed to a entrusted. That some such body is neces tional cooperation on the other. gradual increase of knowledge. A wide, sary has also been acknowledged in all It is of prime importance to resort as nonpolitical dissemination of information the more general plans for disarmament. little as possible to intrusive methods of will serve this purpose in a general way, Sometimes these plans have been am investigation, be they conducted by spies but there would also be occasion to build bitious enough to aim at a kind of "man or through on-site inspections. Modem up a body of reliable knowledge in spe aging agency for disarmament ." That technology is very helpful in this regard, cific cases where doubt has arisen about was the idea indicated in the McCloy since it provides ever more efficient the fulfillment of pledges. Zorin Agreed Principles, which called means for unobtrusively checking events Even in these specific cases the type for an international disarmament organi from a distance. Ra dar and sonar, the of verification and control that relies on zation within the UN. No date was set analysis of radioactive emissions and the police surveillance and aims at a verdict for its creation, but the demand that "the monitoring of telecommunication fre by judicial authority is as far as possible most thorough control should be exer quency patterns are just a few of the less to be avoided. Instead a gradual process cised ... during and after the implemen intrusive methods of surveillance made of mutual contributions by the parties tation of General and Complete Disar available by modern technology. One concerned to clarify matters should be mament" suggests an early inception of such method has had special prominence tried. The Swedish delegation on inter the control machinery. in the recently concluded agreements, national disarmament negotiations has The two draft treaties on general and namely observations from satellites. The sketched such a system of a largely vol complete disarmament submitted in satellite surveillance of launchers for untary control procedure, called "veri 1962 by the U.S. and the U.S.S.R. re land-based strategic missiles, for exam fication by challenge." The official pre spectively differed on several points hav ple, made it unnecess ary for the parties sentation of it in brief form stipulates ing to do with inspection and control but in the SALT I agreement to seek the that under the proposed arrangement "a not with respect to the establishing of an right of direct observation of the missiles. party suspected of having conducted an international disarmament organization, The use of sensors on satellites for underground test, in violation of the which both regarded in principle as making observations raises in the most treaty, would be expected voluntarily to being fundamental. They did not dif acute form problems of ethics that are offer clarifying information to allay sus fer much on the timetable either. The inherent in all attempts at control and picion, the assumption being that the U.S.S.R. wanted such an organization to verification. Control by whom? Because suspected party would itself be vitally begin operating "as soon as disarmament satellite observations are now virtually interested in establishing its innocence. measures are initiated," which is not the monopoly of the superpowers, there An 'invitation to inspection' might be much different from the U.S. formula must be an international demand that forthcoming spontaneously in some in tion to establish it "upon the entry into the observations of militarv satellites be stance and under pressure in more severe force of the Treaty." In the painfully made openly available, at least to the cases of doubt. If such a challenge went protracted but unproductive negotia countries being observed. Only a certain unheeded on several occasions, other tions that have followed, not much at sharing of data of relevance to environ parties to the treaty would acquire the tention has been given to this organiza mental matters is in the offing so far. At right to withdraw from it .... The threat tion, which in its draft shape was quite a a recent meeting of the UN Working of withdrawal might induce the accused full-fledged one with a complex organi Group on Remote Sensing of the Earth party to offerclarification of the suspect zational pattern. by Satellites the representative of the ed event, or if the accusation perSisted, to Several tentative proposals along less U.S. promised that data from his coun invite inspection. The system of 'verifica ambitious lines have been made, how try's satellites would be released regu tion by challenge' would be useful ever. Thus an early initiative was taken larly for international use. The same whether or not obligatory inspections in 1962 by the nonaligned delegations to demand for the internationalization of were envisaged in the treaty. If obliga the Geneva Disarmament Committee to knowledge must be made in regard to tory inspections were envisaged, 'veri set up an international commission of observations of relevance to armaments fication by challenge' would help re scientists for the specific purpose of veri and disarmament. The most desirable duce the size of the unresolved problem, fying a test-ban agreement. Soon there development would be direct intema and if inspection were not envisaged, it after the Swedish delegation pleaded tional management of a satellite system. would help resolve suspicions." that such a scientificcommission be set Internationalization of at least the per In more concrete terms it can be said up on an interim basis even before an tinent data is a sine qua non. It must be that in this scheme of verification by agreement was reached. In 1972 the del realized how great the inequality be challenge the sanction of publicity in ef egations of the Netherlands, Sweden and tween nations is with respect to informa fect replaces the sanction of on-site in Yugoslavia made separate proposals for tion that may be highly relevant for fos spection. Thus the method of deterrence a similar institution, this time in relation tering mutual trust. Sa tellites are the is expected to be effective. The key to to the verification of a prohibition on the most prominent example of the advanced the entire pr oblem of disarmament con production of chemical weapons. techniques for observation that only cer- trol is not reliance on specificformulas in In 1973 I widened the suggestion to

© 1974 SCIENTIFIC AMERICAN, INC encompass all aspects of disarmament control and monitoring . A similar posi tion was endorsed in a statement by P. H. Kooijmans of the Netherlands. My proposal that a central disarmament-con trol organization be set up immediately was motivated by two main concerns. The primary justification for the estab lishment of some organizational frame work on a preparatory basis was that we risk, through ad hoc methods of work, COLLECTION OF INFORMATION heaping on one another control arrange ments that remain unintegrated and even OBLIGATORY DECLARATION unrelated to one another. The second AND NOTIFICATION thesis was that we need such an organ as

GROUND, NAVAL AND soon as possi ble because, in addition to AIR OBSERVATION following the implementation of control arrangements that are already presumed SPECIAL DETECTION AND in various treaties , a constant watch IDENTIFICATION TECHNIQUES should be kept on progress in the gen eral direction of disarmament. INTERNATIONAL EXCHANGE OF REPORTS OR DATA n the wake of the laborious search for I some international agreement incor INQUIRY , porating at least a semblance of disarma ment, signs have become visible that in

ON-SITE INSPECTION BY PARTIES ternational cooperation on control issues might become feasible. The nonaligned

OBLIGATORY AND CONTINUING, nations, supported in general terms but PERIODIC OR IN not strongly by the Western side, have A LIMITED NUMBER struggled in vain to get such operational

ON THE BASIS OF cooperation under the aegis of the UN FREE ACCESS Secretary General incorporated in some treaties. In the current discussions of a ON THE BASIS OF CONSULTATION, COOPERATION comprehensive test-ban agreement the OR INVITATION socialist countries also seem to have moved somewhat closer to acceptance of I NTERNATIONAL SUPERVISION AND INSPECTION organized international cooperation with respect to the exchange of data. An in SPECIALLY ESTABLISHED teresting signal was detected in relation CONTROL ORGANIZATION to a prospective treaty on chemical weap ons in a working paper by seven socialist EXISTING ORGANIZATION states. That side has always been the one upholding the view that "national means"

INVESTIGATION BY UN were sufficientfor verification.In this SECRETARY GENERAL paper a quite comprehensive system of internal control was outlined, based on NATIONAL SELF-SUPERVISION national committees of control, but also AND SELF-INSPECTION .",.

COMPLAINT PROCEDURE

VERIFICATION PROCEDURES relied on CONSULTATION to ensure compliance with the recent multi AND COOPERATION lateral arms agreements have varied widely, as can be seen in this tabular presentation REFERENCE TO CONFERENCE prepared as part of a working paper submit OF PARTIES ted last year by the Swedish delegation to REFERENCE TO the UN disarmament conference in Geneva. INTERNATIONAL COURT In the author's view the task of negotiating OF JUSTICE specific verification and control measures for

RECOURSE TO UN specific disarmament agreements is much SECURITY COUNCIL easier in practice than in theory, "either on the political ground that enough confidence prevails, or on the technological ground REVIEW OF VERIFICATION SYSTEM that sufficiently reliable means of moni.

toring events . _. are becoming available."

© 1974 SCIENTIFIC AMERICAN, INC with a "possibility for publication of re pliance with the international humani civilian benefits and for arms control are ports for general information," the sys tarian rules of war. often not at all congruent. This would be tem also in certain cases to be accom The ideal of openness should be pur the case with an International Ocean panied by the voluntary exchange of in sued first and foremost at the national Regime, if it is established after the Law formation among states. level. Citizens should be counted on to of the Sea Conference concludes its A significantly more active role for this serve as the watchdogs ensuring that dis work. It might, of course, be of assistance international data-exchange system, pre armament agreements are respected and in monitoring the deployment of un supposing also an international commit that any moves in the direction of mili wanted marine installations (for example tee to furnish guidelines for making such tarization are pushed back. When in platforms for military refueling that may reporting comparable and standardized, formation on all matters relating to arms be forbidden). Such a regime , however, was indicated by a group of Russian sci and arms limitation is spread openly must be limited to surveillance in its own entists in a paper on chemical disarma within a nation, the information usually environment; it cannot serve as a guard ment published by the Stockholm Inter becomes available to other nations as against the land-based production and national Peace Research Institute (SIPRI) well. It would obviously be more of a development of vessels or devices that in 19 73. building block for a world system of veri may have to be ruled out for the sake of My proposal is nominally attached to fication if such nationally assembled disarmament. Marine development, en the idea of an international disarmament information could be regularly, system vironmental protection and disarmament organization, since such an organization atically and as a matter of routine nonetheless have a joint stake in the in was in principle accepted by the UN as addressed to an international center for ternationalization of knowledge. early as 1961, but the plan as I now want further dissemination instead of finding There are large areas of interest to dis to present it envisions a system much its way sporadically to more than 10 0 armers that would remain outside the more than an agency. Such a c ompre countries. A broad How of information purview of even the most ambitious hensive system must be organically and would enhance everyone's sense of se scheme for a world system of transna hierarchically built up from the national curity-and security, after all, is the main tional agencies. Here a two-pronged ap level to various international levels, of objective of all verification. proach is imperative. On the one hand, which the one with judiciary functions the access to technologies, particularly should be not only the highest but also he most general feature of such an advanced ones requiring instrumenta the last one resorted to. The design of T approach would include greater pub tion beyond the national means of every the proposed system corresponds to a licity about arms production, arms de country, must be internationalized to structure with four levels. ployment and arms trade. A kind of un gether with the institutionalizing of sec The broad base of such a structure obtrusive, broadside monitoring of dis torial networks for the wide dissemina must be the national means of detection armament dynamics would be gained by tion of scientific and technical data. This and verification that are organized with the more detailed publication of defense would greatly benefit the accumulation in countries not only for internal pur budgets. More specific information can of knowledge on developments related poses (for the control of poisonous chem be requested by separate agreements, in to armaments and disarmament. On the ical agents, weapons production and the cluding information obtained by meth other hand, the specialized need for like) but also for monitoring events ods of distant detection . keeping disarmament matters in focus abroad by remote observation (by means The crucial question then arises of makes it inescapable that an international of seismological stations , analysis of ra whether this requirement calls for the disarmament control organization must dioactive particles in the air and so creation of an international disarmament be established, possessing from the out forth). All such data should be published. organization for centralizing all pertinent set enough independent status and ac Questions referring to the machinery information emanating from national cess to scientific expertise to command needed for control at the national level sources, or whether it is sufficient that respect for objectivity and impartiality. will obviously be handled by each state such information be relayed to one of My proposal is therefore that a new according to its own traditions. In all the likewise international but delimited body should be set up to receive such countries with aspirations to democratic organs in the appropriate specialized notifications and to perform all kinds of government there is already one parlia field. There are, however, few such services for.the cause of disarmamen t. It mentary standing committee or more bodies already in existence that have would be the second level in a control scrutinizing the activities of the military, been given the function of monitoring system, but it would be the first interna with decision-making power closely tied matters of relevance to disarmament. tional level. I suggest that it be called to the sanctioning of allocations. Only the International Atomic Energy the International Disarmam ent Control Parliamentary action, however, is rare Agency has a surveillance function so Organization. Its immediate function ly enough to keep an issue under vital far, and that is limited to surveillance of should be to act as an intermediary, or a civic control. Thus in the working paper the production of nuclear weapons. For clearinghouse, for prOViding knowledge I have mentioned the seven socialist chemical weapons, where the need for about the implementation of disarma states call for the establishment of na an international control body is current ment agreements and also about sponta tional committees comprised of "repre ly being discussed, no suitable existing neous developments in the direction of sentatives of governmental and public agency has been indicated. Other agen disarmament. Such knowledge could be organizations" including "specialists in cies that exist or might be created are provided by member states using their chemistry and economics" with broad likely to have constitutions and con national means of detection, verification responsibilities in relation to the produc stituencies of their own, often outsid e and control. tion of chemical means of warfare. In the framework of the UN, and they might As a supplemental activity the center Sweden a citizens' committee has been not want to add the monitoring of dis should collate knowledge derived from appointed to scrutinize the acquisition of armament to their functions. various open sources: from scientific pub weapons from the viewpoint of com- Moreover, the areas to be covered for lications and st atistics on production,

29 © 1974 SCIENTIFIC AMERICAN, INC trade and the transfer of arms and sensi Such a separation of constituencies be and responses does not lead to satisfac tive raw materials or commodities. It comes particularly necessary when there tory results, an investigation might be should profit by close cooperation with is dispute about whether or not a specific appropriate. If it were, the international international agencies established for treaty has been violated. The "verifica control body would be the correct organ specialized purposes. It could also pro tion by challenge" procedure would then for handling it. For the actual "field in vide guidelines and even establish a more begin by the complaining party's direct vestigations," if such a procedure is in systematic international program for col ing a query to another party (or other order, it may well be that the interna lecting national information, including parties) through the good offices of the tional body should entrust them to vari the setting of rules and procedures for International Disarmament Control Or ous existing expert bodies or to ad hoc making the da.ta of verification compara ganization. If the series of challenges expert groups. The material collated and ble. The process of verificationitself, however, is conceived of as being con ducted by national authorities within in dividual states. k International Disarmament Control Organization might, particularly at the start, function as an open clearing house at the service of all nations by re laying information on disarmament mat ters to them in the form of bulletins. If its competence were broad enough to include its serving as a channel for an obligatory input of data from member states, it would have considerably more impact than the few existing interna tional institutions, such as SIPRI, that have been set up independently to serve a similar purpose. So far no mandatory verification by special investigations has been mad e a part of the proposal for an Internation al Disarmament Control Organization. There will, however, be a need for ex tending the function of the organization to take on the responsibility as coordina tor and referee for collecting evidence of a more active, investigatory character. Even for the future, with the possibility of enhanced world cooperation, it would seem necessary to have an International Disarmament Control Organization func tioning for the purpose of directing spe cific inquiries to existing specialized bodies in cases of disagreement on ques tions of compliance with disarmament treaties. The most critical question is how such a disarmament monitoring service could move toward a more inquisitive process of verification in cases where doubts have been expressed. Such activity would correspond to a third level in the control system. A difficulty is introduced by the fact that different disarmament treaties have, and will continue to have, quite differentlycom posed constituen cies or parties. Here the solution must be that the same secretariat serve a circle of "collateral constituencies," consisting of the full membership of parties concerned in each treaty. Their constituencies would assemble in regular review con ferences, which several treaties already prescribe but which have so far not been SIGNERS AND NONSIGNERS of the Non·Proliferation Treaty are identified on this world given any organizational basis. map. the signers in gray and the nonsigners in color. The principal nonsigners are China.

30 © 1974 SCIENTIFIC AMERICAN, INC accumulated by the international orga the International Disarmament Control responsibility. Only the creation of an nization could then, if one of the parties Organization should never itself pro International Disarmament Control Or wanted to lodge a complaint about treaty nounce verdicts. It should only assemble, ganization, independent of the Security violation, accompany such an accusation collate, coordinate and transmit data. Council with its veto powers, can guar to the appropriate judiciary organ. Pre antee a fair, equitable and expert colla sumably that would be the UN Security he separation of the investigative and tion of evidence. The lack of such an in Council, which can thus be conceived of Tjurisdictional functions, referring stitution is a fundamental deficiency at as being the fourth tier in the control them to different organs, must be made this time, giving arguments to those who system. It would be important, however, clear and exp}icit. The Se curity Council are reluctant to enter disarmament to maintain a strict separation of powers : should not be asked to take on this dual agreements. During the debate in the

France, India, Israel and South Africa. Several of the signers have ent have any intention of ratifying. There are now 84 full parties delayed ratification, and some (for example Egypt) may not at pres· to the treaty together with 22 signers that have not (yet ) ratified.

© 1974 SCIENTIFIC AMERICAN, INC 1945 1946 19 47 1948 19 49 1950 1951 1952 1953 1954 1955 1956 1957 1958 1959 1960 1961 1962 1963 1964 19 65 60 r---,----,---,,---,----,---,----r----,---,----r---,----,----,---,----,----,---,----,----r----,-- U.S.

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KNOWN NUCLEAR EXPLOSI ONS from 1945 through 1973 are only on official announcements by the nations responsible but also tallied by nation in this bar chart according to whether they took on seismic monitoring and other data· gathering techniques em· place in the atmosphere (bars above base lines) or underground ployed by various nations, including Sweden. The totals do not (bars below base lines ); the latter category includes a few cases of include 33 nuclear tests known to have been conducted by the underwater explosions. The totals, which were compiled by the U.S.S.R. before 1958, for which exact dates are unavailable, nor do Stockholm International Peace Rese arch Institute, are based not they include 23 unspecified U.S. explosions that are known to have

32 © 1974 SCIENTIFIC AMERICAN, INC 1966 1967 1968 1969 1970 1971 1972 1973 UN on the convention prohibiting the equipment as wcll as produce manuals production of biological weapons strong and guidelines for the art of monitoring. objections were raised against the hand An agency of this type can be expected ing over of decisions concerning investi to grow on the basis of its own merits as gations directly to the Security Council, a service organ. with its veto power to protect allies and As for deterrence-the threat of dis friends. closure that would discourage clandes There are convincing arguments for tine violations-the process could take a --+---+---1---f---+------+------+ I not postponing action on esta blishing more general, "passive" course. The new such an organizational nucleus. There is, agency could then link up with existing in fact, no reason to wait for agreements or prospective sectorial international in treaty form before starting to monitor agencies, collating and distributing data what happens in one field or another of from many sources. The IJ1ainrequire interest with regard to disarmament. The ment for deterrence is that knowledge be sequence can just as well start with the widened and internationalized; the more monitoring. Indeed, monitoring activities information that is amassed and the more for the verification and control of arms transparent all fields of huinan activity regulation measures might well stimu become, the more repellent becomes the late the emergence of formal agreements. risk of disclosure of any activities that If a target date should be set for launch are formally forbidden or even those that ing such an organizational innovation for just go against the sense of what is com the sake of disarmament, I would sug monly accepted as being internationally gest the Review Conference for Non right-of being in the true interests of Proliferation of Nuclear Weapons in mankind. The denser the data exchange May, 19 75, when the need will make it in a field is, the more it can serve as an self felt strongly and urgently. alarm system, awakening some nation, In regard to the form of organiza some organization, some individuals to tional structure, it would be of value to take action to get more of the unwanted examine whether one might follow fair developments prohibited. ly closely the patt ern set for continuous Here is a promisin g connection be international work on problems of the tween the suggested more informal ap environment. The general constituency proach to the con trol problem and the must be the same worldwide one in both formalization of prohibitions by treaties cases, encompassing the full range of th e with their specific control obligations. UN membership. My contention is that such formalization An interim International Disarmament will be eased when knowledge becomes Control Organization need not be large. more reliable, and \'.hen a consensus on Costs should be kept to the minimum desirable dis armament measures be of administrative necessities. Unlike the comes firmer. Thcse trends grow togeth UN Environment Program, the Interna er, mutually reinforcing each other. tional Disarmament Control Organiza Moreover, it should be emphasized tion would hardly need a fund for oper that any treatv prohibition extends be ations. Like the Environment Program, yond the parties who hayc gone through however, it should have a semi-indepen the formal proc'ess of ratification; the dent status within the UN, its budget al treaty tends to take on a character of I I I I I I I I location being underwritten by the UN. customarv law and can often be argued Such a relative degree of independence to be bindin g on all. At least the psycho is particularly needed for an agency logical and "ethical" impact is not to be whose entire usefulness hinges on its minimized_ Thcrc is a true bond of uni objectivity and freedom from political versal interest in the verifiability of how shackles. loyal and \\-iJesp' cad is compliance not only with prohihitions but also with rules n sum, it appears highly desirable that for good conduct among nations. I a new international body should be Initiatives allowing the UN to study set up for detecting possible transgres the most appropriate forms and func sions of international rules in the field of tions for fulfil lin g the dual task of spread arms and for following changes in the ing knowledge about armaments and of I f I I I I f I verifyin g disarmaments are the most ur quality and quantity of armaments in 1966 1967 1968 1969 1970 1971 1972 1973 various parts of the world. Such a bod y gent ones that I should have wanted to would be responsible for collating the press if I were still a disarmament dele occurred between 196 1 and 1963. Tbe abrupt gate. A proposal for an International Dis change from atmospheric testing to under· relevant data, initiating specific inquiries, ground testing by the U.S., the U.S.S.R. and disseminating its findings and acting as armament Control Organization ought to the U.K. coincides with their signing of the a referee for those who are parties to be forthcoming from some farsighted Partial.Nuclear·Test·Ban Treaty in 1963. The various treaties. Such a body might also member nation, such as the nonaligned 1974 totals would of course include India. have to order the insta llation of specific countries have often proved to be.

An em1SSlon nebula 1S a cloud of interstellar gas that shines by

its own light. Each kind of ion 1n it has a characteristic color,

and three-color photography re()eals how the 10ns are distributed

by Joseph S. Miller

ore than 90 percent of the mat suit more closely approximates the color J. Trumpler at the Lick Observatory con M ter in our galaxy is in the form response of the eye than that of the stan vincingly demonstrated that there was of stars, but the small fraction dard emulsions; moreover, the balance also particulate matter in space capable represented by the tenuous gaseous me of colors reveals the ionization structure of extinguishing the light of stars, and dium in the space between the stars has of the nebula. that most of the apparently empty places an importance for astronomy that is far The existence of interstellar matter along the Milky Way were in fact re out of proportion to its relative abun was not generally recognized until the gions with a high concentration of such dance. This interstellar medium is the latter half of the 19th century. It had particles. The clouds of interstellar dust raw material out of which new stars are been known for some time that certain grains normally reveal themselves by being formed. It consists not only of areas of the sky, largely confined to the blocking the light of the stars behind matter left over from the formation of Milky Way, were strikingly deficient in them, but a few shine by the reflected stars but also of matter that was once in stars. William Herschel and other as light of nearby stars. These reflection the interior of stars and was then re tronomers of the late 18th century and nebulas are useful for studying the prop turned to interstellar space. The medium the early 19th interpreted such areas on erties of the interstellar dust grains, but is therefore part of a cosmic recycling the basis that the stars were simply not they are distinguished from the true process, and it is closely studied for clues there, that these were relatively empty emission nebulas, which shine as a result to what happens in the interior of stars tunnels through the general distribution of the atomic processes going on.within over the course of stellar evolution. of stars. It was also known that there them. The interstellar medium is mostly in were nebulous objects in space that visIble, but here and there it is illumi could not be resolved into stars by tele here are three main classes of emis- nated by the light of stars or it shines scopes. Tsion nebulas, although the atomic with its own light. In the latter case the It was not until 1874, when the En processes that give rise to their radiation atoms of the interstellar gas have been glish astronomer William Huggins ob are basically the same. The first class is ionized-stripped of one electron or served that a nebulosity in the constella made up of the I-I II regions, clouds of more-by the radiation of hot stars near tion Draco had a spectrum characteristic ionized hydrogen associated with places by. These luminous patches are the emis of a rarefied gas, that it was established in the galaxy where stars have recently sion nebulas. that some of the nebulous regions were formed and where their radiation ionizes The emission nebulas can be investi definitely not composed of unresolved the gas near them. H II is the spectro gated in a variety of ways: by direct pho stars. Fifty years later the work of Robert scopic designation for the ionized hydro- tography, by spectroscopy and by ob servations in the radio region of the elec tromagnetic spectrum. Direct photo DYE-TRANSFER PROCESS was used to make a carefully controlled color photograph of graphs provide information on the gross the Great Nebula in Orion. The Orion nehula is an H II region, a region where stars have morphology of the nebula but typically just formed and where their ultraviolet radiation gives rise to ionized hydrogen (H II). yield little knowledge of the physical Three separate black·and·white photographs were made of the nebula with the 36·inch conditions within the gas. Spectroscopic Crossley rellecting telescope at the Lick Observatory. Each photograph was exposed through and radio observations reveal the physi a different color filter and then made into a mat that can absorb a dye. Each mat was dipped cal conditions but usually only in a small into the dye that is the complementary color of the filterused for the photograph: a cyan number of places within the nebula or as dye for the red exposure (top left on the opposite page), a magenta dye for the green ex· (top right) (bottom left). an average for the nebula as a whole, so posure and a yellow dye for the blue exposure Then the mats are placed one at a time in careful registration on a paper that absorbs the dye. The end product that the relation between the physical (bottom right) is a photograph that not only shows how the nebula would appear to the un· conditions and the morphology is seldom aided eye but also reveals the distribution of its Iight.emitting ions. For example, the green well defined. My colleagues and I at the color is radiated by doubly ionized oxygen (0 Ill), that is, oxygen atoms stripped of two Lick Observatory have been taking an electrons. The reddish color is largely due to hydrogen.alpha emission, a wavelength radio other approach: color photography uti ated by the hydrogen atom when its electron drops from the third energy level above the lizing the dye-transfer process rather ground state, or state of lowest energy, to the second energy level. The blue.gray color at the than standard color emulsions. The re- eastern (left) edg e of the nebula is starlight rellected from grains of interstellar dust.

© 1974 SCIENTIFIC AMERICAN, INC © 1974 SCIENTIFIC AMERICAN, INC gen atom; H I is neutral, or un-ionized, hydrogen. The second class of emission nebulas consists of the planetary nebulas. Such a nebula is a sphere or shell of gas that has been expelled by a star in a late stage of its evolution; the gas is ionized by the small, hot star that remains in the center. The term planetary nebula comes from the fact that early observers using small telescopes perceived these round objects as resembling planets rather than the normally pointlike stars. The third class of emission nebulas consists of the rem nants of supernovas, massive stars that have violently exploded near the end of their existence. Supernova remnants shine by at least two different ionization mechanisms, to which I shall return. The three classes of emission nebulas present us with objects that can be stud ied from several viewpoints. First, they are objects of extremely low density and furnish an opportunity to investigate how low-density gases are ionized and excited, and how they interact with ra

RING NEBULA IN LYRA, photographed with the 120-inch reflector at the Lick Observa diation. Second, detailed observations of tory, is an example of a second type of emission nebula_ It is a planetary nebula, which reo their spectra can yield information on suits from an old star ejecting its outer layers. The blue star in the center of the nebula is their chemical composition. Third, since responsible for ionizing oxygen to form 0 III out to a certain radius (green regions), at the various classes of nebulas are asso which point hydrogen.alpha emission and emission from N II dominate picture (red regions). ciated with different stages of stellar evo lution, they can provide information about important events in the life cycle of stars. The source of the energy that heats and ionizes the H II regions and the planetary nebulas is the same: ultraviolet radiation from the hot stars within them. Since hydrogen is by far the most abun dant element in interstellar space, an un derstanding of its ionization is central to investigating the physical processes in the nebulas. It takes 13.6 electron volts (eV) of en ergy to completely strip the single elec tron of the hydrogen atom from the atom when the atom is in its ground state, or lowest energy level. Since this energy is high compared with the energy that is typical of either photons (quanta of ra diation) or subatomic particles in inter stellar space, the majority of the inter stellar hydrogen in our galaxy is in the neutral un-ionized form. Stars with a surface temperature of more than 25,000 degrees Kelvin, however, emit a sub stantial amount of ultraviolet radiation, the photons of which have energies above 13.6 eV. When a hydrogen atom absorbs a photon with an energy greater than 1.3.6 eV, the electron is ejected with DUMBBELL NEBULA IN VULPECULA, photographed with the Crossley reflector, is another planetary nebula whose central blue star is responsible for ionizing the surround a kinetic energy equal to the difference ing gas. Between the central star and the red regions there is a substantial amount of hydro· between the energy of the impinging gen, so that the energetic photons capable of doubly ionizing oxygen are depleted at a point photon and 13.6 eV. The inverse of this well inside the edge of the nebula. Between the central star and the green regions, however, photoionization process, recombination, there is less hydrogen, and the oxygen is doubly ionized out to the edge of the nebula. is also possible: an ionized hydrogen

36 © 1974 SCIENTIFIC AMERICAN, INC CRAB NEBULA, photographed with the Crossley reflector, is an where electrons are being accelerated in a strong magnetic field and example of a third type of emission nebula: the remnant of a suo are emitting synchrotron radiation. The most energetic photons of pernova. The central star of the Crab Nebula exploded in A.D. 1054, the synchrotron radiation are doubly ionizing oxygen atonlS and throwing oft' some of its mass. The bluish central portion is an area arc causing the fiianlentscloser to the nebula's ecnter to glow green.

CYGNUS LOOP, also called the Veil Nebula, is the remnant of an remnant expands its atoms collide with the atoms of the interstellar old supernova that exploded some 50,000 years ago. This photo· medium, forming a shock front. The material of the interstellar graph, made with the Crossley reflector, shows only a fifth of thp medium is swel" up, ionized, compressed and heated by the inter· entire remnant, \\ hich covers an area in the sky three degrees action. It then slowly cools as the shock front mOveS on. As it cools. aeross (six times the diameter of the full moon Llts light originates cleetrons rel"ombine with the ions of the interstellar medium and hy a meduillism different from the syndnotron process. As the enlit radiation in the visible region of the clcetronlagnetic spcetrnm.

37 © 1974 SCIENTIFIC AMERICAN, INC atom (a proton) captures an electron, density, the hydrogen would be almost radiation-bounded; planetary nebulas emitting a photon as it does so. For a completely ionized out to some particu can fall into either category. region in interstellar space to be in equi lar distance from the star, at which point Elemcnts other than hydrogen are librium the rate of photoionization must thcre would be a thin transition zone be ionized in an analogous way. These ele equal the rate of recombination. twecn the ionized gas and the neutral ments can be divided into two types: The processcs of photoionization and gas. This distance, the Stromgren radius, those that have an ionization energy that recombination can be depicted graphi is determined chiefly by the density of is less than that of hydrogen (13.6 eV) cally in energy-level diagrams [see illus the gas and by the total number of ioniz and those that have an ionization energy trations on pages 40 and 41]. The elec ing photons emitted by the star. For the that is greater. The elements with an tron can be captured at any energy level star and the gas to be in equilibrium the ionization energy less than that of hydro of the atom and then cascades rapidly to rate at which atoms are ionized in the gen are ionized throughout most of in the ground statc. It can follow any one entire volume must equal the rate at terstellar space because they do not have of many downward energetic paths, but which the star emits ionizing photons; to compete with hydrogen for high-ener it is possible to accurately calculate what the rate of recombination of the ions ancl gy photons. Those with an ionization will happen statistically in a large num electrons depends on the square of the energy greater than 13.6 eV, however, ber of recombining atoms. The rcsults of density of the gas and to some extent on must compete with hydrogen , and their these calculations, which are in excellent its temperature. Stromgren radii in a particular nebula agreement with observations, indicate Since the relative number of photons are generally equal to or less than the that the transition from the hydrogen emitted whose encrgy is greater than Stromgren radius for hydrogcn. atom's third energy level to the second 13.6 eV is quite sensitive to the star's For example, helium requires photons will produce the most intense visible temperature, thcre is a wide range of with an energy of at least 24.5 eV to re radiation. That radiation is in the red possible Stromgren radii for the hydro move its first electron to form singly region of the visible spectrum at a wave gen in emission nebulas. If the amount of ionized helium (Hc II ) and 55 eV to re length of 6,563 angstroms and is desig gas around a hot star is small enough for move its second electron to form doubly natcd hydrogen alpha. the star to have at least cnough photons ionized helium (He III). Most H II regions to ionize the entire cloud, the nebula is and planetary nebulas contain enough 'lihe pioneering work of Bcngt Strom- said to be gas-bounded. Alternatively, if high-cnergy photons to ensure that he gren in the 1930's on the theory of the star does not generate enough ra lium will be at least singly ionized the photoionization of hydrogen demon diation to thoroughly ionize the cloud, throughout most of the volume in which strated that if the star wcre cmbedded the nebula is said to bc radiation-bound hydrogen is ionized, but only thc hottest in a uniformly distributed gas of low ed. Most H II regions are believed to bc stars found in the center of planetary

[0 II] t

Ul t:: z � > cr: <{ cr: f

cr:m � � ziii w f- �

3,500 4,000 4,500 5.000 5,500 6,000 6.500 7,000 7,500 WAVELENGTH (ANGSTROMS)

COLOR RESPONSE OF' THE EYE I black) is compared with the gen alpha I H",) at the wavelength of 6,562 angstroms. The braekets color response of the three separate hlue, green and red photo· indicate that the two lines of oxygen are "forbidden" transitions, graphs used in the dye·transfer prot'ess for constructing the color that is, transitions that are not normally observed in lahoratory photographs of the gaseous nebulas. Also indicated are the emis· spectroscopy. Standard color emulsions tend to be insensitive in sion lines of singly ionized oxygen (0 II) at the wavelength of the green region of the spectrunl and thus do not record eluiS5ion 3,727 angstroms, the two lines of doubly ionized oxygen 10 III) at of 0 III. Neither the eye nor the blue exposure is sensitive to the the wavelengths of 4,959 and 5,007 angstroms and the line of hyrlro. emission line of 0 II in the near-ultraviolet region of the speetrunl.

© 1974 SCIENTIFIC AMERICAN, INC nebulas are capable of prodUcing large mechanisms that keep the temperature kinetic energy of the particles in the gas regions of He III. Light of a wavelength in the range between 5,000 and 20,000 and the amount of radiation present. that is characteristic of an electron re degrees. The most important of these With gaseous nebulas different tempera combining with He III to form He II is mechanisms is the inelastic collision of tures are generally needed to describe never seen in the H II regions of our gal electrons with partly ionized atoms of these parameters. Therefore the power axy. Even in the planetary nebulas with elements heavier than hydrogen and he ful general equations that can be applied the hottest central stars the Stromgren lium, that is, collisions where an electron to describe a gas in thermodynamic radius of the He III is always smaller gives up some of its kinetic energy to equilibrium cannot be employed with than the radius of H II, a direct result of excite the electrons still bound within gaseous nebulas, and one must treat each the relatively few photons with an en the ion to higher energy levels. The process individually. Nonethe less, the ergy above 55 eV emitted by any star bound electrons then drop back to the availability of large computers and in [see illustration on page 42]. ground state and emit radiation that creasing knowledge of atomic processes For every 10 atoms of hydrogen in in leaves the nebula. have made possible considerable prog terstellar space there is one atom of he Since a typical electron in the gas has ress in theoretical studies of the physical lium, but the next most abundant ele a kinetic energy of only a few electron structure of gaseous nebulas. Not only ments (carbon, nitrogen and oxygen) are volts, only those atoms that have energy are the general features of that structure only a thousandth as abundant as hydro levels within a few electron volts of the well understood but also the theories gen. They too are subject to the photo ground state are readily excited by in bear up well when their predictions are ionization-recombination process, but elastic collisions. Therefore the small compared with the observations. because of their low abundance their amounts of neutral hydrogen and helium ability to compete with hydrogen and present in the nebula are of no impor ince the radiation from the ions that helium for high-energy photons is small. tance for cooling, since their lowest ex S are indicators of the degree of ioniza The atoms that do manage to become cited states are more than 10 eV above tion in a nebula is emitted at widely sep ionized have a characteristic Stromgren the ground state. Ions of oxygen, nitro arated wavelengths in the visible region radius for each state of ionization. The gen, neon and other trace elements, how of the spectrum, gradations in the ioniza zone of highest ionization is usually ever, do have low-lying excited states. tion structure of a nebula are correlated closest to the central star. The ionization And even though their abundances are with variations in color that can be pho structure of an emission nebula is there small compared with the abundances of tographed. Standard color films, how fore the result of a fairly complex inter hydrogen and helium, they are quite ever, suffer from a color response that play between the radiation emitted by efficient in reducing the energy content not only is uneven over differentparts of the central star and the depletion of this of the gas. It happens that the radiation the spectrum but also depends on the radiation as it proceeds outward and they emit results from transitions of the length of the exposure ti me. Therefore ionizes the gas. excited electrons that violate the sim such films are not suitable for photo What factors determine the tempera plest forms of the rules of quantum me graphing astronomical objects in a con ture of the gas at a particular point in chanics and are therefore called forbid trolled and repeatable way. Their limita an emission nebula? Again the individual den transitions. Although the forbidden tions are particularly serious for the color processes are fairly simple and the total transitions are not normally important in photography of nebulas because the two situation is complex because a large the laboratory, they are of paramount important green lines of 0 III fall in a number of processes are at work simul significance in the low-density gases of region of the spectrum where standard taneously. Basically the temperature at interstellar space. color emulsions are quite insensitive. any point is determined by the balance One of the most important nebular At the Lick Observatory, George H. of heating processes and cooling proc coolants is oxygen. In the singly ionized Herbig and Merle F. Wa lker, aided by esses. Heating results directly from pho form 0 II, radiation is produced in the the advice and technical skill of Eugene toionization: the electron ejected when ultraviolet region of the spectrum as a A. Harlan and the late Rulon Watson, an atom is ionized interacts in a matter result of the collisional excitation of the have resurrected the dye-transfer process of seconds with other electrons and ions lowest pair of energy levels. 0 II can be for studying the emission nebulas. In this in the gas, contributing its energy to the responsible for a large percentage of the process, which was once the principal overall kinetic energy of the gas. Recom energy lost in nebulas of relatively low means of making high-quality color pho bination, however, favors the lower-en ionization. In nebulas of higher ioniza tographic prints, three separate black ergy, slower-moving electrons. The ra tion the doubly ionized form 0 III is and-white pictures are made of an object diation given offby the electron as it re often a strong coolant through transi through three different color filters. The combines generally has no effect on the tions from its first excited level to the individual photographs are then made energy balance of the gas because it ul ground state, which emit green light at into mats that can absorb dyes, the timately escapes from the nebula. The the wavelengths of 5,007 and 4,959 ang amount of the dye absorbed being re net result is that the gas as a whole gains stroms. These two emission lines are lated to the intensity of the original ex kinetic energy,. since on the average the often among the strongest radiated by posure. Each mat is then dipped into a electrons being recaptured from the gas nebulas in the visible region of the spec different dye, and the mats are succes by recombination are less energetic than trum. sively placed in careful registration on a the electrons being added to the gas by Even with the trace elements acting special paper that absorbs the dyes from photoionization. as coolants to balance the heat generated them. If the dyes and filters are carefully by photoionization and recombination chosen and the photographic exposures f photoionization and recombination the nebula is not in thermodynamiC are carefully balanced, the dye-transfer I were the only processes inside a neb equilibrium. For a gas to be in such process is capable of producing con ula, the gas could heat up to a temper equilibrium there must be a single tem trolled and repeatable color pictures. ature of more than 100,000 degrees perature that characterizes the level of The human eye is unable to perceive K. There are, however, other heat-loss excitation, the degree of ionization, the colors very well at the low light levels

© 1974 SCIENTIFIC AMERICAN, INC characteristic of most diffuse astronoPli brating the emulsions of the photograph color response of the eye, but the results cal objects, and the dye-transfer pictures ic film to the wavelengths of light ad are far superior to what can be obtained were intended to match the color re mitted by the filters. Standard color with standard color film. sponse of the eye as closely as possible charts were used for laboratory tests and It turned out that, although the orig in order to show how the objects would selected astronomical objects were cho inal intent was to match the response of actually look if the colors were seen di sen for field tests. The final product is, the eye, the color balance exceeded our rectly. The matching was done by cali- of course, only an approximation of the expectations in revealing the ionization

• 1 •

II 14 14 14 - r- 6 6 6 - 5 5 5 - 4 4 4 r--- 12 12 12 -=: 3 _------_.".1 3 3 r-

10 2 10 2 10 2 r------

C7i f--C7i f-- C7if-- --' --' --' 0 0 0 > 8 > 8 > 8 z II: Z II: Z II: 0 w w 0 w 0 CD II: CD II: CD II: f-- f-- :::;: f-- :::;: (..J :::;:::::> (..J ::::> (..J ::::> w w z w z z --' --' --' --' --'w w--' !!;!. w !!;!. > !!;!. > >- > >- w 6 z w 6 CJ w 6 CJ --' 0 --' II: --' II: I I W W >- f= z « >- z CJ>- CJ f-- CJ w w II: II: II: w (3 w Z ill Z Z X Z 0 Z 0 w W ill f= w f= >- « « CJ f-- f-- 4 II: 4 (3 4 (3 ill X X Z ill W W

2 2 2

o o o

I I

PHOTOIONIZATION of hydrogen is illustrated in this energy.level diagram. The neutral, RECOMBINATION is the inverse of photo. or un.ionized, hydrogen atom is in its lowest energy state when its single electron (gray) ionization. Here the single proton of a is in the ground state (Levell at left) with respect to the single proton (color) of the nucle· hydrogen ion captures an electron (left), us. For an atom of hydrogen to be ionized a quantum of incoming radiation must have an which cascades down to lower energy levels energy of at least 13.6 electron volts. Atom absorbs radiation and ejects electron with a in the atom, emitting radiation as it does so. kinetic energy equal to the difference in energy of quantum and 13.6 electron volts (right). The energy of the typical recombining eIec·

© 1974 SCIENTIFIC AMERICAN, INC structure of the emISSIOn nebulas, par The Orion nebula is probably the losity is related to the rest of the nebula ticularly the structure of the ionized oxy most notable of all the H II regions both and the stars. gen, which is an excellent tracer of the because of its closeness to the earth Like the Orion nebula, most other H overall ionization. A spectacular example (1,500 light-years) and because of its II regions show a wealth of det ail that of the wealth of information that can be brightness, although the total amount of complicates efforts to study their physi obtained from such photographs are the matter in it is not overly large compared cal structure. Their complexity reflects pictures of the Great Nebula in Orion. with the average H II region. In the pho the rather chaotic distribution of the in tograph of the nebula's center on the terstellar medium in regions where stars cover of this issue of Scientific Ameri have recently formed. Many of the plan can the four bright stars known as the etary nebulas, on the other hand, are Trapezium (for their geometric arrange quite regular and symmetrical and must ment) are clearly visible. The brightest have originated with the gentle, smooth of the four is a very hot star with a tem ejection of gas by the parent star in the perature of about 40,000 degrees K. It interior. Exactly how a star ejects its is the one chiefly responsible for ionizing outer envelope, however, is still entirely 14 the nebular gas. The intense green color unknown. of the gas is due to the radiation of the The prototypical planetary nebula is two forbidden lines of 0 III. To the the Ring Nebula in Lyra, which appears southeast there is a reddish border in the top photograph on page 36. A around the nebula where there apparent hot blue star is located at the center of 12 3 ly is not enough 0 III to generate the the "doughnut hole" in a region of gas green radiation, so that the red radiation that is particularly low in density. The from hydrogen dominates. There is also a parts of the nebula closest to the star contribution from the red lines of sing ly show the green of the radiation from 0 (N II), III, and there is a relatively clear, sym 2 10 ionized nitrogen an ion found in regions of relatively low ionization. metrical transition to the red of the hy drogen and nitrogen at the outer edge. he transition from the predominance Spectroscopic observations. show that at Cii rr I- III ..J of 0 to the predominance of hy this reddish outer edge there is also an 0 8 > drogen and nitrogen shows up more increase in the strength of the emission a: z II w 0 clearly on the longer-exposure photo lines of 0 in the ultraviolet region of Ol a: ::;: I- graph of the Orion nebula at bottom the spectrum, but since the color photo ::> () z W ..J right on page 35, which shows the tenu graphs are not sensitive to ultraviolet ra ..J W � ous outlying portions of the nebula as diation the emission from hydrogen and > w > ..J 6 (!) well as the central regions. Although the nitrogen dominates the picture. Never a: w brilliant central features are considerably theless, the color transition corresponds (!)>- z a: w overexposed and the green from 0 III is to a distinct place where the energetic w z z III w 0 not faithfully reproduced, to the west photons capable of ionizing 0 are ex j:: < one can see that the radiation extends hausted. Another example of such a re I- 4 C3 with decreasing intensity as far as the gion of transition from 0 IIIto 0 II in a X W main body of the nebula can be detected. nebula is the Dumbbell Nebula in Vul In that direction it seems there is enough pecula, which appears in the bottom radiation to ionize all the gas, so that 0 photograph on page 36. III exists throughout the entire volume. The color photographs thus illustrate 2 In other words, in its western region the in a beautiful and clear way the opera nebula runs out of gas before it runs out tion of a rather complex set of phenom of ionizing photons, and that region is ena associated with the photoionization gas-bounded. of a diffuse gas by a star or stars. The To the north and southeast, however, photographs have accurately guided de o photons capable of ionizing oxygen to tailed spectroscopic observations of the form 0 III are depleted, and there are Ring Nebula and the Dumbbell Nebula large regions where the overall level of with the 120-inch reflecting telescopeat ionization is lower. In those regions the the Lick Observatory. Moreover, they color of the nebula is dominated by the convincingly verify the results of theo red from hydrogen and nitrogen. Finally, retical calculations. in the extension of the nebula to the southeast it can be seen that the material .,As I have mentioned, remnants from is divided into two regions, one primarily supernovas represent a separate red and the other blue-gray. Again the class of gaseous nebulas whose source of red is emitted by hydrogen and nitrogen; energy is not necessarily the photons the blue-gray, however, is starlight re from a central star. The best-known rem tron is less than that of a typical electron ejected during photoionization. In the il· flected by interstellar dust. In that region nant, the Crab Nebula in Taurus, pre lustration the energy is captured to the third there is relatively little ionized gas, but sents an example of gas ionized by the energy level (right); if electron now drops the geometry of the gas and the dust is synchrotron radiation emitted by elec just one more energy level, then it would complex enough to make it somewhat trons spiraling at high velocities in a emit red radiation of hydrogen.alpha line. unclear how the dusty reflection nebu- magnetic field. The spectrum of the radi-

© 1974 SCIENTIFIC AMERICAN, INC ation from a star approximates the spec relatively young remnant that has not two dissimilar components: a relatively trum of a black body, or ideal radiator, yet begun to interact to any large degree smooth bluish region and many multi and the distribution of the energy at dif with the interstellar gas of the galaxy colored filamentsand pieces of filaments ferent wavelengths falls offrapidly in the around it. Most supernova remnants we [see upper photograph on page 37]. The far-ultraviolet region of the spectrum. observe are much older and derive their blue region is the place where light is Synchrotron radiation, unlike the black luminosity from the fact that the expand generated by the synchrotron process. It body radiation, can show a flatter energy ing shell of the remnant collides with the is believed the strong magnetiC field of distribution extending far into the ultra surrounding interstellar gas. The colli the pulsar at the center of the nebula is violet or beyond it. The Crab Nebula sion gives rise to a shock front in which responsible for the acceleration of the emits some of its energy in the X-ray re the gas swept up by the expanding shell electrons to the high speeds required to gion of the spectrum. Thus synchrotron is highly ionized; the light we observe is emit the synchrotron radiation [see "Su radiation is composed of many more generated behind the shock wave, where pernova Remnants," by Paul Gorenstein high-energy photons than the radiation the ions and electrons are recombining and Wallace Tucker; SCIENTIFIC Ai\IER from stellar sources, and the resulting and cooling. The Cygnus Loop, also ICAN, July, 1971]. ionization structure of a supernova rem known as the Veil Nebula, is a good ex Since the synchrotron radiation ex nant can be quite differentfrom the ample of this phenomenon. tends into the far ultraviolet, it ionizes structure of an H 1I region or a planetary Interpreting the color photographs of the gas in the filaments, which then glow nebula. either the Crab Nebula or the Cygnus with the colors characteristic of their The Crab Nebula is the product of a Loop is not as clear-cut as interpreting chemical composition and ionization. As supernova that exploded in the year those of either the H II regions or the can be seen in the photograph, the dis 1054 and is therefore an example of a planetary nebulas. The Crab Nebula has tinction between the red filamentary re-

70 60 50 40 30 ENERGY PER20 PHOTON (ELECTRON15 VOLTS) 10 100 I I I I I HII 0 I 1�1'1I�0\1I1 I 011 TI' I 90 I--- It � V� � 80 J '""" 70 I �

I- / ::> 0.. � I- 60 ::> 0 >- C!l a: --- w 50 � r-. z - w w '" > ----- i= « � � -' 40 w a: ...... � � 30 � / 20 /' / 10 I // V ( o o 100 200 300 400 500 600 700 800 900 1,000 1,100 1,200 1.300 1,400 WAVELENGTH (ANGSTROMS)

CURVES OF THE DISTRIBUTION OF ENERGY over the far gions. The relative energy output indicates how much energy per ultraviolet region of the spectrum are shown for two stars at dif wavelength one star puts out with respect to the other. For exam ferent temperatures. The distributions are adjusted so that both ple, at a wavelength of 250 angstroms the hotter star is emitting stars emit the same amount of energy at a wavelength a little longer some nine times as much energy as the cooler star. Energy per pho than 900 angstroms. The color curve is for a star with a temperature ton at different wavelengths is indicated across top. Also shown is of 100,000 degrees Kelvin, typical of the central star of a planetary minimum energy of ionization for singly ionized helium (He II), for nebula; the black curve is for a star with a temperature of 50,000 singly and doubly ionized oxygen (0 II and 0 III), for neutral heli degrees K., representative of the hottest stars found inside H II reo um (He d, for neutral hydrogen (H [) and for neutral oxygen (0 [j.

© 1974 SCIENTIFIC AMERICAN, INC gions and the green ones is not at all terms of the theory of ionization by radi started out with material composed en symmetrical or orderly. It is possible, ation of a low-density gas. I believe our tirely or almost entirely of hydrogen and however, to work out the three-dimen theoretical understanding of the details helium. As a result of the nuclear syn sional distribution of the filamentsin of this complex process is quite good. It thesis of heavier elements in the interior space. Correlating their spatial arrange is now possible to extend the study of of stars and the recycling of matter by ment with the colors in the photograph ionized interstellar gases and consider supernova explosions the galaxy has and with measurements of the intensity them in the context of other astronomical gradually been enriched in the heavier of their various spectral lines indicates problems. elements. The composition of the plane that the regions of higher ionization (the One important problem for which tary nebula in M15 suggests that oxygen green filaments) tend to be located closer emission nebulas can supply some valu and neon were built up more rapidly to the center of the nebula than regions able answers is the question of the chem than the metals, since even in this very of lower ionization (the red filaments) ical composition of the matter in our old object these lighter elements have and may even be embedded in the por galaxy, both in the past and at present. abundances that are within 10 percent tion of the nebula emitting the synchro Armed with the knowledge of the physi of their abundances in the interstellar tron radiation. Such an arrangement cal structure of nebulas one can inter medium as it is currently constituted. would imply that the higher ionization is pret the strengths of the various emission Many details have yet to be worked out, principally due to the fact that the high lines from different elements in terms of but the overall picture seems to be er intensity of the ionizing photons in the the relative abundances of the same ele soundly sketched. nebula's center more effectively over ments in the nebulas. The results are We might then ask if the abundances comes the balancing process of recombi quite interesting. It turns out that H II of the elements in the filaments of the nation. regions like the Orion nebula, which are Crab Nebula confirm this picture, since At greater distances from the Crab young objects, and the planetary neb they represent material being returned Nebula's center the gas seems to be sub . ulas, which are made by stars that are on to the interstellar medium at the present jected to radiation of lesser intensity, and the average several billion years old, time. U nfOl'tunately for astronomers the thus even though the energy distribution have abundances of helium, neon, oxy Crab Nebula generates more questions over the spectrum of the radiation may gen, argon, nitrogen and sulfur that are than answers. A recent analYSis of the be the same, the equilibrium between very similar. It appears, then, that plan abundance ratios of the elements con photoionization and recombination will etary nebulas are the ejected outer layers ducted at the Lick Observatory by be established at an overall lower state of stars whose chemical composition was measurement of the intensities of the of ionization. Complicating the situation not much changed by nuclear reactions spectral lines of a few filaments selected even more is the fact that in the Crab earlier in the life of the star. Such evi by consulting the color photographs Nebula several states of ionization of a dence must be kept in mind during fu showed that the ratio of helium to hydro given element coexist in one place in ture detailed investigations of how gen was much larger than normal: be stead of being more simply stratified into planetary nebulas are ejected from their tween six and 10 times larger. It is not regions of different Stromgren radii, as parent stars. possible at present to determine the they are in the H II regions and the Furthermore, the composition of the abundance of metals, but at least it ap planetary nebulas. material out of which the old stars in the pears that the ratios of oxygen, neon, ni Whereas the Crab Nebula is now a planetary nebulas formed differs little trogen and sulfur with respect to hydro little more than 900 years old, the Cyg from the composition of the present-day gen are close to those found in the H II nus Loop originated with a supernova interstellar medium. Thus we are actu regions. These results vary from what we that exploded perhaps 50,000 years ago. ally looking far back into the past by had expected for a supernova remnant, The rapidly expanding debris of the star studying, for example, the planetary but it is quite likely that the Crab Neb has collided with a large amount of in nebula located in the globular cluster ula originated in a very unusual super terstellar gas during this interval, grad- M15 in the constellation Pegasus. The nova explosion. As far as we know it is . ually slowing in its expansion from an star responsible for this object is believed unique in our galaxy. In any case there initial rate of approximately 10,000 kil to be at least 10 billion years old and is still much left to be le arned about the ometers per second to its present rate of was formed at a very early stag e in the formation of the elements during the his some 100 kilometers per second. The evolution of our galaxy. Studies of other tory of the galaxy. visible light from the nebula is the direct stars in the cluster indicate that in them result of this continuing deceleration as the abundance of metals such as iron is he study of emission nebulas has the expanding remnant ionizes the gas of deficient with respect to the abundance Treached maturity. The basic physical the interstellar medium. Although de of hydrogen by a factor of more than 100 mechanisms operating appear to be well tailed theoretical models of this process compared with those abundances in the known, so that we can understand the have been devised and the calculations sun, which is a much younger object. rich detail of the color photographs in are in excellent agreement with the ob The planetary nebula, however, shows terms of processes at the atomic level. served emission spectrum of the rem about the same ratio of helium to hydro With this knowledge we have been able nant, the physical phenomena respon gen as the Orion nebula, indicating that to address questions concerning the sible for the gross color variations from the abundance of helium has not chemical evolution of the galaxy. Some place to place are still unknown. changed much over most of the history astronomers are beginning to turn their of the galaxy. The abundance ratios of attention to the ionized gases in more We have seen that in color photo- oxygen and neon with respect to hydro distant objects in the universe. We can graphs three intrinsically different gen in the planetary nebula are about a now hope to considerably increase our kinds of objects-H II regions, planetary tenth as great as the ratios in the Orion knowledge of these objects as a result of nebulas and the Crab Nebula-display nebula. what we have been able to learn by an intricate structure that can be under Our present view of the chemical evo studying the emission nebulas closer at stood in a rather straightforward way in lution of the galaxy is that it very likely hand.

© 1974 SCIENTIFIC AMERICAN, INC CILIA IN MOUSE OVIDUCT move eggs along the tube from the the University of California at San Francisco, are about .25 micro· ovary toward the uterus. The cilia, enlarged some 23,000 diameters meter in diameter and project a few micrometers above the surfaces in this scanning electron micrograph made by Ellen R. Dirksen of of the cells lining the oviduct, which are covered by microvilli.

CILIA ON TETRAHYMENA, a protozoon, propel the one·celled graph made by Birgit Satir of the University of California at Berke· animal through water. The cilia cover the entire surface of the or· ley and Jean·Paul Revel of the California Institute of Technology. ganism, enlarged 3,500 diameters in this scanning electron micro· Cilia are same diameter as oviduct cilia but about twice as long.

The hairlike organelles that propel swimming cells or move liquids

over fixed cells are composed of sheaves of nlicrotubules. The cilia beat when the microtubules, powered by ATP, slide past one another

by Peter Satir

ilia are "eyelashes" that are found dium in which a mat of cilia functions then working at the Rockefeller Institute on the free surfaces of a wide va cause the individual cilia to interact in a for Medical Research. Their pioneering C riety of cells, ranging from single special way, producing a metachronal, electron-microscope studies and those of celled organisms such as protozoa to the or out-of-phase, wave that propagates others had established the remarkable epithelial cells of human mucous mem through the mat. identity of the ultrastructure in a wide branes. Some cells have dense fringes or In 1961, when the subject was last re range of cilia in different organisms. mats of cilia and some have only one or viewed in Scientific American, not much Each cilium could be seen to consist pri a few of them, in which case they are more than that was known about ciliary marily of a sheaf of ffiaments, or tubular called flagella. (Bacteria also have flagel motion and its mechanism [see "Cilia," elements, arranged in what came to be la, but these are an entirely different or by Peter Satir; SCIENTIFIC AMERICAN, called the 9 + 2 pattern, with nine dou ganelle.) Whatever their superficial ap February, 1961]. The structure of the blet elements surrounding a central pair pearance, all motile cilia have essentially organelle was beginning to be uncov of singlets. The sheaf of filaments, called the same structure and the same basic ered, on the other hand, largely as the an axoneme, was surrounded by and en function: to move a stream of liquid. We result of work by Irene Manton of the closed in an extension of the cell mem are beginning to understand how they University of Leeds and by Don W. brane, which meant that it was essential move. Fawcett and Keith R. Porter, who were ly a protruding portion of the cytoplasm Ciliary motion can have either of two eITects, depending obviously on whether the cell is a free-swimming one or is fixed in place. Cilia attached to a moving cell, such as a paramecium or a spermato zoon, propel it through a liquid; cilia at tached to fixed cells, such as those that line the gill of a mussel or the trachea or reproductive tract of a human being, move a liquid over the surface of the cells. Most cilia beat between 10 and 40 times a second, but the form of the beat ) is quite variable. The flagellum consti tuting the tail of a sperm propagates a wave that undulates as it moves from the �� base of the tail to the tip and drives the sperm head forward; in the case of a sea urchin sperm that wave moves in a sin gle plane at velocities of about half a millimeter per second. The cilia on the gill cells of the mussel M ytilus beat in a more complex way: an oal'like, planar ef fective stroke drives water over the gill '=l and is followed by a whiplike return stroke in which the cilium swings out to one side as it regains its original position. CILIARY MOTION takes various forms; these are two typical patterns. Successive waves Given the size of cilia or flagella, the hy propagated toward the tip of a flagellum (left) move water (colored arrow) and thus propel drodynamics are suggestive of an oar the sperm head in the opposite direction. The beat of a typical cilium (right) consists of a working in molasses rather than in water. straight.armed effective stroke (white cilia) that moves a liquid (colored arrow), followed The viscous forces produced in the me- by a curling return stroke (gray cilia), often in a third dimension (out of plane of paper).

© 1974 SCIENTIFIC AMERICAN, INC of the cell. Below the axoneme could be discerned a basal body: a short cylinder identical in structure with a centriole, one of the organelles that constitute the poles of the mitotic spindle during cell division in most animal cells. Electron micrographs showed that the outer dou blets of the axoneme were more compli cated in structure than the central sin glets; successive cross sections made it clear that the two kinds of filaments and the individual elements of the doublets were of different lengths. In 1961 the substructure of the individual tubular elements had not yet been revealed by high-resolution micrography and the bio chemistry of the cilium was still rudi mentary. There was speculation about how the filaments might interact to make the cilium move, but the experimental information was lacking. One could not even be sure that the basis of ciliary mo CROSS SECTIONS OF CILIA from the gill cell of a mussel are enlarged about 100,000 diameters in this transmission electron micrograph. Each consists of a cylindrical axoneme tion lay solely within the axoneme, or in enveloped by an extension of the cell membrane. The axoneme, .2 micrometer in diameter, deed that the cilium itself beat actively. includes a ring of nine doublet microtubules surrounding two single central microtubules. urrent understanding of the mecha- C nism of ciliary motion is the result of observations and experiments in many laboratories, which I shall present here SUBFIBER A somewhat out of chronological order. One of the basic findings was the dem onstration that the cilium is not simplv CILIARY MEMBRANE a waving appendage powered by con tractile elements elsewhere in the cell. That was established in an elegant ex· periment performed by Stuart Goldstein, Michael Holwill and Norman Silvester of the University of London. They aimed a laser microbeam at the base of the cilium of a living protozoon, Crithidia, and thus severed the cilium without damaging it. The severed cilium swam off on its own. Repeated experiments indicate that the isolated cilium keeps going as long as its energy reserves hold out. To study the biochemistry and kinetics of cilia it was essential to have a "model system" that could be subjected to ex perimentation. Following the lead of muscle-cell investigators, in the early 1950's Hartmut Hoffmann-Berling of the CENTRAL Max Planck Institute for Medical Re MICROTUBULE search in Heidelberg added glycerin to ciliated cells and tissues. The result DOUBLET was exciting: once the glycerin was MICROTUBULE SPOKE HEAD removed and the cells were washed, the addition of adenosine triphosphate CENTRAL SHEATH INTER DOUBLET LINK (ATP) to the preparation caused the cilia to beat. This indicated, and further ex periments have confirmed, that ATP is

INDIVIDUAL CILIUM CROSS SECTION like those in the micrograph at the top of the the energy source for motility in cilia, as page is diagrammed. Each doublet microtubule has two sub fibers, A and B; arms project it is for most cellular activity. from subfiber A toward the next microtubule's subfiber B. The axis is an imaginary line de· The precise effect of the glycerin be fining the plane of the cilium's effective stroke, bisecting the bridge, the central microtubule came clear about 10 years later when pair and the doublet designated No. 1. Cilium is viewed here from base toward tip. Frank Child and I, working at the Un i-

© 1974 SCIENTIFIC AMERICAN, INC DETAILS OF CILIARY STRUCTURE are revealed in two micro· of the cilium (left) shows two doublets attached by radial spokes to graphs of longitudinal sections of Tetrahymena cilia, made by Bir. the sheath surrounding the central micro tubules. A section nearer git Satir, and a high.power micrograph of part of a cross section of the surface (center) shows two of the outer doublets, with arms pro· a mussel.gill cilium, made by Fred D. Warner of Syracuse Univer· jecting from one toward the other, forming a ladderlike pattern. sity and the author. The longitudinal sections show the axoneme The cross section (right), which enlarges the cilium some 550,000 and the wrinkled ciliary membrane. A section through the middle diameters, resolves the microtubules' subunits: the protofilaments.

PROTOFlLAMENT CENTRAL MICROTUBULE 8 CENTRAL

ULTRASTRUCTURE OF CILIUM is diagrammed schematically dynein. The construction of an individual doublet is shown in more (le/t), largely on the basis of the interpretation of electron micro· detail (right). The cylinders are composed of tubulin molecules graphs. The central sheath apparently consists of a series of tilted arrayed in rows (13 in subfiber A, 10 or 11 in subfiber B) that hoops, to which the doublets are connected by the heads of radial constitute protofilaments. As in the drawing on the opposite page spokes. The doublets are linked by molecules of a protein, nexin. and in the cross· section micrographs, the view is from base toward The two sets of arms, inner and outer, are molecules of the enzyme tip, that is, the tip of the cilium is toward the bottom of the page.

© 1974 SCIENTIFIC AMERICAN, INC versity of Chicago, examined glycerinat ciliary membrane is to maintain around sequently refined by Barbara and Ian R. ed cilia in the electron microscope. We the axoneme the proper concentration of Gibbons and their colleagues at the Uni could see that the glycerin had destroyed A TP and also of certain essential ions versity of Hawaii. They removed the the membranes of the cilia and the cell such as magnesium. After the membrane heads from sea-urchin sperm and treated but had left the 9 + 2 axonemes virtual is destroyed by glycerin it therefore be the tails with a detergent, Triton, instead ly intact, and the naked axoneme was comes necessary to supply the ATP and of glycerin. The resulting model tails, capable of ciliary motion. In the living the necessary ions from the outside, and which are simple membraneless 9 + 2 cell ATP, produced by mitochondria, by the same token it becomes possible to axonemes, swim just like living sperm. which usually lie near the base of the vary the concentration of ATP and other Moreover, the precise dimensions of cilium, diffuses out toward the tip of the substances for experimental purposes. their beat can be controlled by altera axoneme. Anessential function of the This investigative technique was sub- tions in the medium in which they are reactivated. In particular the concentra tion of ATP determines the frequency of the beat.

he energy to move the cilium is sup- Tplied, as in other cellular work proc esses, by the breakdown of ATP through hydrolysis into adenosine diphosphate (ADP) and phosphoric acid. The enzyme that accomplishes this hydrolysis in cilia was identified by Ian Gibbons and A. J. Rowe, working at Harvard University, as an ATPase, which they named dynein. Gibbons found that he could extract dy nein from axonemes if he put them in a solution containing a chelating agent, which in effect sequesters the magne sium ions. When he examined the dy neinless axonemes in the electron micro scope, he found they lacked a specific structure characteristic of normal axo nemes: a series of projections called arms that protrude from one side of each of the nine outer doublets. If he then BEATING CILIA on the surface of a cell interact so that in one direction, usually perpen· took a solution containing the dyneinless dicular to the direction of the effective stroke, they are out of phase. The result is a meta axonemes and added dynein and the chronal, or out-of.phase, wave that appears to move over the mat of cilia. In this diagram right amount of magnesium ion to it, the 1 2, 3 4 the cilia in row are at the end of the planar effective stroke. Those in rows and are dynein was reincorporated into the axo in successive stages of the curling return stroke. Those in row 5 have ended the return nemes. And at the same time that the stroke and are beginning the effective stroke, wMch has ended in row 7 (the same as row 1). return of dynein was signaled by the re appearance of ATPase activity, the arms also reappeared. In other words, the arms are dynein molecules. Many additional details of the con struction of the doublets and singlets of the axoneme are now clear. Each tubular element is actually a microtubule, a structure found in the cytoplasm of many kinds of cells, including the axons of nerve cells. Microtubules are composed of small protein molecules called tubu lins. There are at least two kinds of tu bulin molecule in each microtubule. They are strung together like Poppit beads in a row to form protofilaments; the protofilaments are arrayed alongside one another, something like individual columns of building stones, to make up the wall of the microtubule.

METACHRONAL WAVE in the lateral cilia of mussel-gill cells (foreground) was pre· Each axonemal doublet is composed B. served hy instantaneous fixation with osmium tetroxide. The scanning electron micrograph of two subfibers, A and Subfiber A is was made by the author and Dirksen. The directions of the effective stroke and the meta a complete microtubule with 13 proto chronal wave are about as they are in the diagram at the top. Cilia in different stroke positions filaments. Subfiber B is shorter in length in preparations like this one are examined to determine the pattern of subfibers at their tips. and has fewer protofilaments-only 10 or

4 SUBFIBER A 8 3 SUBFIBER B

DOUBLET NO. 1 '----" DOUBLET NO. H 6 DIAMETER OF AXONEME (d)

SLIDING OF MICROTUBULES is manifested by differences in bend is given by the formulas. Because the length of the inner arc the pattern. of subfibers near the tip of tbe cilium. Here the rela· is proportional to the radius (r) and the length of the outer arc is tions among sliding, bending and tip pattern are shown for two proportional to that radius plus the diameter of the axoneme (d), doublets, Nos. 1 and 6, in three stroke positions: straight up, bent the difference in length (Il)is proportional to the axoneme diam· in the effective·strokedirection (right) and bent in the return· eter (d). As the three base·to-tip cross·section diagrams of the in· stroke direction (left). The colored arrows mark equal distances dicated part of each cilium show, in the straight position all sub· along the microtubules from the beginning of the bend. Because fiber B's should be present but in the bent positions subfiber B the microtubules are flexible but of constant length the doublet on of the doublets on the outer side of the bend will be missing; the the inner, concave side of a bend must slide tipward. The resulting expectation is confirmed by the three electron micrographs displacement (Il)can be measured at the tip, at the end of subfiber (top). When the dynein arms canse microtubules to slide past one B or at the end of the bent region. The length (l) of the arc of the another, shear resistance in the cilium changes sliding to bending.

© 1974 SCIENTIFIC AMERICAN, INC 11-so that it sits alongside sub fiber A teins," by John M. Murray and Anne University of Chicago in 1964. I was try like an intersecting, incomplete cylinder. marie \Veber; SCIENTIFIC AMERICAN, ing to determine the sequence in which The dynein molecules, it became clear, February J. If the ciliary microtubules the nine doublets terminate at the tip of are spaced along subfi�r A in two differ could "walk along" one another by a cilium. I did that by examining the cilia ently oriented rows; they form two sets means of their dynein arms, one could of cells that had been fixed quickly in of arms (inner and outer) that point envisage that, given the right sequence of osmium tetroxide, thus "freezing" the toward subfiber B of the adjacent dou activity and appropriate shear resistance cilia in the middle of a metachronal wave blet and are long enough to bridge the within the axoneme, bends would form and making it possible to look at the tips space between microtubules. This is and would propagate in such a way as to of cilia in different positions in the elec reminiscent of the structure of a muscle produce the movements characteristic of tron microscope. I found that whereas fibril, in which the ATPase ends of myo cilia. The hypothesis that this is the different cilia that were in the identical sin molecules on the thick filament point mechanism of ciliary motion is called the stroke position appeared to have identi toward and, under the right conditions, sliding-microtubule hypothesis. cal tips, the tip pattern in cilia in one onnect with thin filaments so as to slide stroke position was not the same as it was sets of filaments past one another and he first experimental evidence that in cilia in another position. A special fea thus cause the muscle to contract [see Tmicrotubules slide when cilia move ture in the gill-cell cilia of the freshwater "The Cooperative Action of Muscle Pro- was obtained in my laboratory at the mussel I was examining enables one to number each microtubule unequivocal ly: there is a diamond-shaped bridge be tween the two micro tubules that are at the leading edge of the cilium when the cilium is in its effective stroke, that is, when it is actively moving liqUid. If an imaginary line connecting the center of the bridge with the middle of the central pair of single microtubules is extended across the cilium, it transects a doublet on the opposite side. This doublet, which

ADJACENT DOUBLETS in a longitudinal section near the tip (right) of a mussel.gill is at the leading edge of the cilium dur cilium are enlarged about 60,000 diameters in this micrograph. As the arrows indicate, sub ing its recovery stroke, is designated No. fibers B of the two doublets end at different points; the distance between the ends is the dis 1. That makes the doublets that are con placement caused by the sliding of the doublets. Both subfibers A continue toward the tip. nected by the bridge Nos. 5 and 6. What I found was that when the cili um was bent so that doublets Nos. 5 and 6 were at the leading edge, No. 6 ap peared to be longer at the tip than No. 1. When doublet No. 1 was at the leading edge, on the other hand, it appeared to be the longer. I concluded that doublets No. 1 and No.6 must actually be about the same length and that they must be displaced as the cilium bent in a manner consistent with the sliding of the micro tubules past one another [see illustration on preceding page]. Tip differences can be measured quite accurately for every microtubule doublet in the axoneme, and the amount of displacement can also be measured at several points along the axoneme. The displacement is strictly proportional to the amount of bend, as would be predicted by the rigorous ap plication of simple geometric relations if the microtubules do not actually change length during the beat. The constant of proportionality depends on the diameter of the axoneme, since that is the amount by which the radii of curvature of the inner and the outer microtubules differ. RADIAL SPOKES are seen in electron micrographs made by Warner. A flattened·out sub Whereas cilia vary enormously in length, fiber A from a blowfly sperm tail is enlarged some 250,000 diameters and negatively stained from about a micrometer (a thousandth (top), revealing the protofilaments and the projecting spokes. The periodicity of the spokes of a millimeter) to two millimeters, the is accentuated in a micrograph of a section of a mussel.gill axoneme (bottom). On the lower side of the axoneme, where the spokes are directly in the plane of the section, they are seen diameter of the axoneme is invariably to be arranged in triplet groups with a major repeat (arrows) of .086 micrometer. The print about .2 micrometer. The constancy of was made by multiple exposure of the negative, which was advanced .086 micrometer be diameter suggests that the sliding mech tween successive exposures. The image remained sharp because the periodicity is invariant. anism must be quite general for these

© 1974 SCIENTIFIC AMERICAN, INC organelles in many different species and tissues. At the University of California at Berkeley, together with Fred D. Warner of Syracuse University, I have been able to carry the geometric analysis a step further. We have found that there is a built-in ruler along the microtubules in the form of a repeat pattern of the pro jections known as radial spokes, which appear to connect the doublets to the central sheath. The repeats mark off stretches exactly .086 micrometer long in all the cilia we have studied. The peri SLIDING AND BENDING are uncoupled when axonemes are subjected to trypsin, which> odicity is invariant in both straight and breaks down some of their protein structures, notably the spokes. Keith E. Summers bent regions of the axoneme, effectively of the National Heart and Lung Institute and Ian R. Gibbons of the University of Hawaii demonstrating that the micro tubules do treated sea·urchin sperm tails with detergent and trypsin and added ATP. The sequence not contract at all. of dark·fieldmicrographs (top) shows how the axoneme elongates and becomes thinner This interpretation was amply and as the ATP causes the microtubules to slide along one another. The diagram (bottom) strikingly confirmed by Keith E. Sum indicates schematically how the sliding of spokeless microtubules could have this effect. mers and Ian Gibbons at the University of Hawaii. They took detergent-treated sperm tails and exposed them briefly to Such attachment would provide ef though the structural basis for micro the protein-digesting enzyme trypsin, so fective resistance in places where bends tubule sliding is presumably present. that the trypsin broke up some of the develop, and thus bring about bending, The biochemistry of these cilia is not well more complicated linkages in the axo when the doublets move past one an established, however, and there may be neme but left the microtubules and the other. If that is the case, then in axo deficiencies other than spoke attachment dynein arms more or less intact. When nemes in which the attachment is de that explain the mutant behavior. (A fur they then added A TP, the axonemes no fective the cilia should bend with diffi ther difficulty is that there are unusual longer swam; instead they fell apart! culty or even be nonmotile. Sir John sperm tails that have axonemes with mi Summers and Gibbons made dark-field Randall and his colleagues at Kings Col crotubules without the 9 + 2 arrange photomicrographs of the axonemes at lege London discovered mutants of the ment and possibly without spokes, but the moment the ATP reached them. At single-celled green alga Chlamydomonas that nevertheless generate bends.) that instant each axoneme grows longer, in which the nine doublet microtubules The assumptions of the sliding-micro and correspondingly thinner, as groups and the arms look structurally normal tubule hypothesis have been further of doublets manage in effect to walk but in which the central sheath and the tested by Charles J. Brokaw of the Cali along their neighbors and then on be central pair are improperly formed. Such fornia Institute of Technology, who de yond them [see top illustration on this mutants are indeed nonmotile, even veloped a computer program based on page]. Clearly the trypsin uncouples the sliding of microtubules from the bend ing of the axoneme.

he radial spokes are among the struc- Ttures that are digested by trypsin. So are certain interdoublet links com posed of a protein called nexin. It seems likely that one of these structures nor mally provides the shear resistance within the axoneme that converts sliding into bending. The best candidate for this function, in 9 + 2 axonemes at least, seems to be the radial spokes. For one thing, they are aligned in the direction in which the bending takes place. For another, Warner and I have found that the configuration of the spokes is differ ent in straight regions of the axoneme from what it is in bent regions. In straight regions most of the spokes stand perpendicular to the microtubule dou COMPUTER SIMULATION of a beating sperm tail (top) approximates the real thing blet at which they originate; in bent re (bottom) when the data supplied to the computer reflect the assumptions of the sliding. gions many of the spokes are tilted and microtubule hypothesis. Charles J. Brokaw of Cal Tech devised a computer program that perhaps stretched, as would be expected in effectgenerates a working model of a sperm flagellum. Each line in the computer print· if they had been firmly attached at both out represents the sperm tail in a successive beat position. The superposed flash micro· the doublet and the central sheath when graphs, which were made at the rate of 120 flashes per second, are of a swimming sea· the doublet slid forward. urchin sperm. The white oblong shapes (left) are successive images of the sperm head.

© 1974 SCIENTIFIC AMERICAN, INC microtubule sliding that can simulate rection of the stroke of some of its cilia. blet to particles in the adjacent ciliary the movement of a flagellum.The pro In such cases the fundamental sliding membrane, which are arranged in a gram generates values for bending rates microtubule mechanism must be affect "ciliary necklace" with several strands along the flagellum, which are then used ed by specific cellular controls. Roger o. [see illustration below J. The sliding of to print out successive portraits of the Eckert, Yutaka Naitoh and their collabo microtubules when cilia move could dis swimming organelle. The computer-sim rators at the V niversity of California at place parts of the necklace and there ulated flagella develop and propagate Los Angeles have found that ciliary re by alter the permeability of part of the bends that have wave variables identical versal is caused by an influx of calcium membrane to certain ions. The alteration with those of living or detergent-treated ion into the cell. The same ion is known might in turn provide a feedback path 9 + 2 axonemes [see bottom illustration to be the signal for muscle contraction. way that could regulate the magnitude on preceding page J. The computer print The point at which the calcium acts on or direction of sliding. Such a mechanism outs are much less like actual sperm-tail the sliding mechanism of the axoneme is may function in cells other than ciliated patterns when equations representing still not clear, and yet the V.C.L.A. ob ones, where microtubules may also be contraction of the microtubules are sub servation is very important in that it sug connected to intramembrane particles. stituted for sliding. gests how changes in the concentration Microtubules, as I have indicated, are of ions within a cell may be directly re present in many cells and they may be f the sequential bends that arise along lated to the behavior of the cell and its capable of sliding past one another. In I a relatively long axoneme are opposite cilia. Investigation of processes that alter doing so they may serve as general or and symmetrical, the undulating axo ciliary behavior has considerable signifi ganelles of transport, not only moving neme swims forward in a straight line. cance for human health, since the arrest membrane particles but also moving Many sperm tails do just that. Some cilia of ciliary motion by various agents {such chromosomes during cell division or and flagella are capable of behavior as tobacco smoke} can lead to pathologi moving enzymes and other molecules much more complex than simple, con cal changes in the underlying cells. along the axons of nerve cells. All such tinuous forward swimming, however. One possible mechanism for relating ideas are quite speculative at this stage For example, when a paramecium en microtubule sliding and ion concentra of investigation, but it is clear that the counters an obstacle, it can back away tions is a "microtubule-membrane com verification of the sliding-microtubule and then go ahead in a slightly different plex" we have noted at the base of cilia mechanism of ciliary motility has im direction. It does so by altering and in that are capable of complex behavior. portant implications for many unsolved some cases completely reversing the di- Fibers extend from each axonemal dou- questions in cell biology.

CILIARY MEMBRANE

NECKLACE PARTICLES

CILIARY NECKLACE is seen in a "freeze fracture" image of a of particles near the base of the cilium. The diagram (right) is a mussel.g ill cilium (left). The preparation was frozen and then reconstruction of the microtubule-membrane complex that appar· fractured, cleaving the ciliary membrane; a cast of the interior of ently gives rise to the necklace. The membrane has been split open, the membrane was made, so that the electron micrograph of the revealing the necklace particles, which are connected to the mid· cast is a replica of the membrane interior, showing three strands dIe of the doublet microtubules by wineglass-shaped structures.

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transportation of nerve-gas munitions members of Congress, their staffs and across their borders and in part because their outside advisers. These are the con European nations are uneasy about the clusions of a statement issued last month large quantities of nerve-gas weapons by the research and policy committee of in the stockpiles of the North Atlantic the Committee for Economic Develop Treaty Organization (NATO). Repre ment (CED). The statement was drawn sentative Wayne Owens, Democrat of up by a subcommittee on decision mak Utah, has estimated that to replace the ing for national security chaired by existing stock of nerve-gas weapons with Franklin A. Lindsay, president of the binary ones would cost between $1 bil Itek Corporation; the project director lion and $2 billion. was Thomas C. Schelling of Harvard Meanwhile in Geneva the Conference University. of the Committee on Disarmament The statement points out that the use (CCD) has been meeting five months a ful life of a major new weapons system year for two years. Twice a week dele "typically does not begin until nearly a gates of 25 nations listen to one anoth decade after production is authorized; its er discuss the elimination of chemical lifetime then extends through that sec weapons from the arsenals of the world. ond decade and beyond." Congressional Binary Subtraction Under the 1972 Biological Weapons committees reviewing strategic weapons Convention the U.S. and other powers should therefore focus on their long-term n a little-noted action, coinciding committed themselves to negotiate in justification and should insist that re closely with the resignation of Presi good faith toward an early agreement to quests for authorization be made "in I dent Nixon, the House of Represent ban such weapons. the context of projected second-decade atives approved by a vote of 31 5 to 70 At hearings held by a new subcom needs." Moreover, components of the an a resolution urging the Senate to ratify mittee on arms control and disarmament nual defense budget should be projected the 1925 Geneva Protocol banning the of the House Armed Services Committee, for fiveyears, and "items requiring long first use of chemical weapons in war. Fred C. Ikle, director of the Arms Con lead time should be the subject of actual Although the U.S. was one of the origi trol and Disarmament Agency, testified: five-year authorizations." Each year Con nal signers of the protocol, it is the only "If we start on a new type of production gress would revise the authorization for major power that has not formally rati program [of binary nerve gases], it be the next four years and add a new fifth fied it. Five years ago, when President comes even harder to envisage construc year authorization. Nixon sent the protocol to the Senate tive arms-control agreements limiting Decisions on U.S. weapons systems are for ratification, he declared the U.S. competition in chemical weapons." The strongly influenced by what the U.S.S.R. would never be the first to use lethal House evidently heeded the testimony is doing and are also intended in part to or incapacitating chemical weapons, but of Ikle and others who spoke against the influence Russian decision making, ac he insisted that the protocol did not new program. In transmitting the resolu cording to the statement. Congress can cover tear gas and herbicides, both of tion urging the Senate to ratify the Ge properly participate in the process of which were then being used in Viet neva Protocol the House subcommittee bargaining on arms limitation by author nam. At about the same time the United suggested that the Senate has the power izing or failing to authorize a specific Nations General Assembly was support to ratify the protocol without excluding program, and even by indicating that it ing by a vote of 58 to three a resolu herbicides and tear gas. might authorize one. There is danger, tion declaring that tear gas and herbi however, in adopting programs simply as cides were covered by the protocol. Arms and the Congress bargaining chips, the CED subcommit As part of its recent action the House tee warned. "There are certain diplo also deleted from the Department of ongress should have a more effective matic tactics for which the legislative Defense budget a request for $5.8 mil C voice in making decisions on na branch of government in a democratic lion to start production of a new gen tional security, particularly with regard society is just not suited." The bargain eration of binary nerve-gas weapons. to strategic-nuclear-weapons systems, ing-chip tactic encourages indecisive These are devices that contain two rel and to that end organizational and pro ness and either can saddle the country atively nontoxic ingredients in separate cedural changes are necessary. Planning with weapons that were meant to be containers that are mixed and react to and the authorization of funds should be merely threats or can be exposed as dan form a potent nerve gas only after the projected over a longer period. Funding gerous bluffing. The CED subcommittee device is on its way to the target. Evi should be better coordinated with the re believes "Congress has a positive role to dently the Department of Defense quirements of arms-control negotiations. play in the process of strategic arms lim would like to replace its present enor And Congress should have available to it itation bargaining" but urges Congress mous stockpile of nerve-gas weapons professional resources for the evaluation "to be doubly cautious about authorizing (estimated to contain 40 million pounds of proposed military programs; that will any system that is justifiedprincipally in of gas) with binary weapons, in part require, among other things, improved terms of its bargaining value." because state governments object to the access to secret military information for Government programs have in general

© 1974 SCIENTIFIC AMERICAN, INC become "increasingly technical, complex be accounted for if the value of G is de and esoteric," and moreover military pro creasing. Indeed, such a decrease was grams are veiled in secrecy. It is there predicted as early as 1937 by P. A. M. fore difficult for Congress to evaluate Dirac, and it is also incorporated in the military requests. The CED subcommit cosmological theory put forward by Fred tastes tee recommends the establishment of a Hoyle and J. V. Narlikar and the gravi . it new professional research organization: tational theory developed by Carl H. expenSIve "an office, institute or institution for re Brans and Robert H. Dicke. ...and is. search and evaluation" that could help Thomas C. Van Flandern of the U.S. Congress to play "a stronger role in Naval Observatory and his colleagues scrutinizing and reviewing the defense have been examining the motion of the budget and weapon programs." Congress moon by timing occultations, or eclipses, should also encourage the existence of of stars as the moon passes in front of "diverse centers of analytic strength" by them. The observations are made with regularly calling for independent advice respect to two independent standards of and testimony from organizations and in time. One standard is atomic time, which dividuals outside the Government. is measured with an atomic clock whose Central to proper Congressional par rate is presumed to be uniform; the other ticipation is "the need for security clear is ephemeris time, which is based on the ance, for access to classified information orbital motion of the earth around the and the right to have custody of it, and sun and is thus subject to any changes for participation in classified discussion resulting from a change in G. Observa and examination as well as analysis and tions made with respect to both stan research." Security clearance is now the dards show that the times at which the responsibility of the executive agencies. moon occults specific stars in its path get Members of Congress, sitting in execu later as the moon recedes from the earth Ma.defrom

Women's Size ___Color ____ _ that the rate of the earth's spin is slowly rate at which planets other than the earth N ame' ______decreasing. Most of the retardation is (notably Mercury) are receding from the

Address. ______caused by the friction of the tides. The sun. The third is a sensitive laboratory

Cit ______y, _ angular momentum lost by the rotating experiment to detect whether or not the State Zip ____ earth is transferred to the moon, which rate of spin of two small masses rotating o Send me FREE your new color catalog of over 1000 exciting outdoor products. absorbs it by receding from the earth at a between two large ones decreases with rate of three centimeters per year. There time as a result of a decreasing gravita is, however, a puzzle: the rate at which tional attraction between the two sets of the earth has been slowing down is only masses. about half the rate that would result from If the occultation results are correct Dept. OSC, 1737 Airport Way S .• Seattle, Wa. 98124 ------tidal friction alone. The discrepancy can in indicating that the force of gravity is

© 1974 SCIENTIFIC AMERICAN, INC slowly weakening, the puzzle about the discrepancy in the rate at which the earth's rotation is decreasing would be solved. Moreover, theories that predict that gravity is weakening also predict I� �akes a lewel head that the solid earth is expanding at the rate of about a centimeter per century, and a lowlnahean �o be which could have something to do with large-scale geological processes such as a Del�a profeSSional. continental drift. And if the value of G You meet all kinds of people a free stopover, whatever's is indeed decreasing, it would mean that the general theory of relativity is incom with all kinds of travel best for the customer. plete, since it does not take such a phe problems in a Delta ticket You could get by with less. nomenon into account. office. And you have to know A lot of folks wouldn't know the all the answers. difference. But when it comes Enrichment by Laser But not just pat answers. to people, a Delta Air Lines professional couldn't �ser methods have been successfully You try hard to come up with employed by several laboratories to a lower fare, an easier care more. A-DELTA The airline run by profeSSionals enrich natural uranium in its content of connection, a faster route, the fissionable isotope U-235. Moreover, it is reported that hig h levels of enrich ment can be achieved in a single pass through a laser device. The technique consists in selectively exciting atoms of U-235 with laser light tuned to a wave length that is not absorbed by the more abundant atoms of U-238, then ionizing the excited U-235 atoms and collect ing them electrostatically. Although the technique has clear military implications, its chief attractiveness lies in its poten tial for producing cheaper enriched ura nium fuel for nuclear power plants. In the U.S. uranium is currently en riched by the gaseous-diffusion method developed in the 1940's. The enrichment step accounts for about a third of the total fuel-cycle cost of a nuclear power plant. By 1983 the demand for enriched uranium for such plants is expected to exceed the capacity of the present diffu sion facilities, and new facilities will have to be built. Enrichment by high-speed gas centrifugation has been widely dis cussed, but the feasibility of the process on a large scale has yet to be demon strated. According to a study by David F. Edwards of Colorado State Univer sity, the laser technique opens up the possibility of an isotope-separation proc ess with the effectiveness of the gaseous diffusion and gas-centrifuge methods at a small fraction of their cost. The first report of uranium enrich ment with a laser was released last year by the Exxon Nuclear Company and the Avco Everett Research Laboratories. Since that time similar successes have been reported by groups in Israel and at the Lawrence Livermore Laboratory. In the Livermore experiment vaporized .uranium metal was illuminated by laser light at a wavelength of 5,915.4 ang stroms and by ultraviolet radiation from a mercury-vapor lamp. The laser light

© 1974 SCIENTIFIC AMERICAN, INC was absorbed by U-235 but not by U-238. (The absorption peak for U-238 IF YOU BUY is .1 angstrom lower.) The ultraviolet radiation then kicked some of the elec trons out of the excited U-235 atoms , and the positively charged ions were A NEW CAMERA collected in a negatively charged cup. The flow of U-235 was too small for sig nificant accumulation in the cup, but the FIVE YEARS FROM NOW, effect could be measured in a mass spec trometer. The laser-excitation method can be used to separate isotopes of other ele THIS IS THE KIND ments. Experiments in the U.S.S.R. have demonstrated that nitrogen 15 can be separated from nitrogen 14 by the photo YOU WILL BUY. dissociation of ammonia. Workers in the U.S. have reported the laser s eparation of hydrogen, boron and bromine iso topes. According to Edwards, isotope Eventually, all fine35mmcameraswill offer the innovations that have separation by laser excitation promises caused every major photographic magazine to acclaim the Minolta XK. to provide many of the natural isotopes at a cost many times lower than the costs Today the XK is the only camera that combines the versatility of a prevailing. total system with the advantages of electronics. The result is unprece dented creative freedom and handl ing ease for the involved photographer. Poor Man's Satellite An electronically controlled titanium shutter is at the heart of the Minolta XK. It will operate manually or automatically. In automatic mode, I-I igh-altitude balloons have been used it sets itself for correct exposure, depending on the lens opening you for astronomical purposes since the select. The built-in metering system is activated automatically as you mid-1950's. They have attained altitudes hold the camera. Since the Auto-Electro viewfinder shows shutter speeds up to 155,000 feet, and the flights have and lens opening, you need never lose sight of your subject as you focus lasted as long as several days. Currently and compose. And if light is insufficient for correct exposure, a signal in the National Scientific Balloon Facility the finder tells you not to shoot. at Palestine, Tex., a division of the Na The XK's shutter is unique in other respects, as well. Its range of tional Center for Atmospheric Research, is conducting experiments with a type of speeds is wider than on any camera in the world: from 16 full seconds to balloon that is capable of attaining sim I/2000th second. And it is amazingly quiet, vibration-free and accurate. ilar altitudes, of carrying payloads of Because your camera needs will almost certainly change, the XK is some 500 pounds and of remaining aloft designed to change with them. You may switch to any of four interchange for many months and repeatedly circum able viewfinders or nine focusing screens. A full navigating the earth. system of interchangeable Rokkor-X lenses, rang The balloon being used for such long ing from fisheye to super-telephoto, provides still duration flights is a superpressure bal more versatility. loon: its internal pressure is slightly higher than the external pressure of the atmosphere when it reaches the de sired altitude. Most standard balloons are zero-pressure balloons: their internal pressure is the same as the external pres sure. At night the gas cools and dimin ishes in volume until it is denser than the surrounding air, with the result that the balloon sinks unless ballast is periodical ly released. When the balloon runs out of ballast, its flight comes to an end. In a superpressure balloon the gas remains at a pressure higher than that of the sur If you are thinking seriously about the purchase of a fine 35mm reflex rounding air even after the balloon cools, camera, consider one that reflects the technology of the future, not the so that there is no need for ballast. past: the Minolta XK. For an illustrated brochure and the name of your Since the superpressure balloon is fly nearest retailer, write to Minolta Corporation, Advanced Systems Divi ing at an altitude of some 30 miles, it is sion,lOI Williams Dr., Ramsey, N.J. 07446. In Canada: Anglophoto, Ltd.,P.O. above 99 percent of the earth's atmo sphere. It is therefore a good observation platform for long-term astronomical in THE ELECTRONIC MINOLTA XK vestigations that cannot be pursued from the ground. Such investigations include

Look. we've all got to take a littlesometime, ..but this guy goes looking for it. Wayne Sutterfield is Refuse Commissioner for the City of St. Louis and he has 900 tons of garbage on his hands each day. So Wayne Sutterfield believes in new approaches to solid waste management. The city's garbage is continually combed for steel cans. Sutterfield's powerful magnetic conveyor belts literally suck them right out of the garbage at the rate of about 78.000.000 a year. Steel's unique magnetic propertymakes it possible. The reclaimed cans are marketed to a steel producer who recycles them during the production of new steel products. The economics help Sutterfield and the people of St. Louis 'clean up' in the bargain. The same thing is happening today in 20 cities across the country. But steel can recovery isn't the only exciting thing that happens to the city's garbage. St. Louis burns some 300 tons of its combustible solid waste each day (mixed with coal) to generate electric power in a conventional boiler at the Union Electric Company. That power is enough to serve 25.000 homes. The program reduces air pollution. saves landfill and conserves coal. St. Louis was the first American city to try it. but it won't be the last. Sometimes it pays to take a little garbage. For more information write. Tinplate Producers, American Iron and Steel Institute, 1000 16th Street, N.W., Washington, D.C. 20036 . c s •• • and lean up in the bargain.

��- Tinplate Producers American Iron �A�l and Steel Institute "C";dedtf'o°-'

Meet Walt Welles, conservationist, former navigator on an oceanographic schooner. Loves the sea. Worries over what man might do to it. Hates oil spills. But he also likes what petroleum does for his enjoyment of nature. Quick-drying sails made from petrochemical feedstocks. A maintenance free fiberglass hull, also petroleum-derived. An auxiliary engine that couldn't go anywhere without diesel fuel. So he wants conservation-plus adequate supplies of petroleum. Which, to Walt Welles, is simply a matter of realistic trade-offs on conserva tion issues involving oil. Offshore drilling? "Yes, within reason," he says. "I certainly don't want to look at nothing but oil wells when I put to sea. But I'm told a single production platform today does the job of many earlier ones." We could also tell him some of our plans for the future, like producing oil on the bot tom of the sea. In many cases with no visible platforms at all. This new system is being tested right now. As to building deepwater ports to handle very large tankers: "I'm excited, as a conservationist, that crude oil could be unloaded at a buoy 10 or 20 miles out to sea, then carried by submarine pipeline to storage tanks ashore. That means fewer vessels in our ports. Fewer risks of collision and oil spills. And no need to dredge our harbors, damaging the eco-system." It also means that we'd be able to handle our imported crude oil in the most economical way. "The trick," Welles says, "is to make the ocean work for all of us. Yield her fish and her oil. Without messing up the critical balance of nature. Or the beauty we all love." Well said, Walt. We couldn't agree more.

Mobir

Like all the best-selling compacts from Check the form on this superstar. Inside, there's Plymouth, Duster's game is strong and complete. comfortable seating for a fivesome. On the small car circuit, five is one better than par. And Duster's trunk takes honors among small cars, because it's big enough for the longest of drives. There aren't any holes in Duster's game. It's priced lower and has more room than some very popular imports. So, you see, some small cars just drive for show. And some putt-putt to save you dough. But Duster does it all. So now , you know.

You get great distance from a Duster. You'll get a good long roll from a gallon of gas. And speak ing of distance, with unleaded gas, Duster's new , spark plugs can go as much as 30,000 miles America's without replacement. Which fits in just fine with Duster's money-saving Electronic Ignition No.1 System (no points or condenser to replace). selling small car 'A�A�CHRYSLER MOTORS CORPORATION comes from Plymouth.

© 1974 SCIENTIFIC AMERICAN, INC the recording of cosmic rays, the collec (Advertisement from the JS&A Group-America's tion of interplanetary dust and micro largest single source of electronic calculators meteorites and the study of many celes and other space-age consumer products.) tial phenomena at wavelengths in the electromagnetic spectrum that are blocked by the atmosphere. The cost of flyingan experiment aboard a superpressure balloon is only a few percent of the cost of placing it in orbit around the earth. Accordingly the superpressure balloons have been called "poor man's satellites." While the bal loon is aloft investigators can remain in radio communication with it in order to issue commands to their apparatus and retrieve data. At the end of the flight the payload can be recovered. Thus the bal loon also provides a relatively inexpen sive way for an investigator to make a trial run of an experiment that may later be put into space.

Lineups

anagers and other baseball strate- Measuring only 2'1:/' x 2'1:/' x 2'1:/', CUBa is America's newest space-age product-small enough to gists give much thought to the bat M conveniently fit on your desk or big enough to ting order, following such precepts as get you up in the morning. putting a good runner first and a big hitter in the "cleanup," or fourth, spot. Does it make any difference? R. Allan Freeze of the University of British Co lumbia, writing in Operations Research, says that "the effect of using the best Introducing CUBO-the new batting order rather than the worst is solid-state digital alarm clock. less than three extra wins per 162-game The clock that thinks for itself. season." Freeze conducted a computer simula tion of some 200,000 baseball games, For years, alarm clocks were dull . _ . even programming the computer with the those with snooze buttons and fancy dials. main features of the Sports Illustrated Dull until CUBa, a new solid-state digital Unexpected, unique, and totally new-great Baseball Game, which is normally played alarm clock that not only wakes you up, looks pretty and tells perfect time, but has its own reasons to give CUBa. But it's also a gift that by the repetitive throwing of three dice. brain-just like a pocket calculator. will be used everyday-a great way to be re (With his program he could simulate a membered. Available in white, orange or lime. THE VIRTUES OF BRAIN POWER set of 10,000 games in less than three BUI L T BY THE EXPERTS CUBa's brain performs several functions: minutes.) For his data he chose two CUBa is manufactured by Corvus, a sub 1. Accurate time-keeping Just plug the CUBa groups of players from the New York sidiary of Mostek Corporation, one of the into a wall socket and count on the precise nation's leading manufacturers of integrated Yankees. One group consisted of nine time to within five seconds per year. The sol calculator circuits. To order your CUBa, sim of the batters and four of the pitchers id-state electronic circuit uses the latest com ply send your check for $32.45 ($29.95 plus puter technology, has no moving parts and is on the 1970 team and therefore, accord $2.50 postage and handling-Illinois residents totally silent. add 5% sales tax) to the address shown below. ing to Freeze, represented "an average 2. Precise alarm system You can set CU BO' s If you wish to charge CUBa to your Master grouping of major-league players." The digital alarm for a specific time, i.e., 6: 59, Charge, BankAmericard, Diners Club or Amer or and then precisely at that time ican Express credit card account, call our toll other group was "a composite lineup of 7: 03, 8:31 CUBa will wake you up with a gentle elec free number and order CUBa at no obligation all-time Yankee greats" and so was "of tronic beeping sound. today. 2 week free trial • one year warranty Hall of Fame caliber." Freeze simulated Practical snooze button There's no snooze NATIONAL 3. IMMEDIATE button to worry about. Simply reach over and INTROOUCTORY games with the teams in the traditional DELIVERY $2995 PRICE turn CUBa upside down. The alarm will stop lineup, a second lineup putting the hit and resume precisely ten minutes later. ters in descending order of productivity 4. Controlled intensiW A small integrated and a third putting them in ascending light measuring sensor tells CUBa's brain to order of productivity. He reached the lighten or brighten the light-emitting diode digits on its display so you can see it com � "hardly surprising" conclusion that the fortably in the dark or in bright light. NATIONAL SALES GROUP traditional lineup is helpful. "What may 5. Several other features A small red light DEPT. SAC-1 4200 DUNDEE ROAD be surprising is the very small influence pulses every second. A power failure or NORTHBROOK, ILLINOIS 60062 brownout sets off special indicators telling of what most baseball connoisseurs CREDIT CARD BUYERS CALL: you to check your clock's accuracy. And the would consider to be a monumentally time or alarm setting is quickly set by press absurd strategy," putting the big hitter ing just two buttons. In Illinois(800) (312) 498-6900 323-5880 ©JS&A Group, Inc .• 1974 (say Babe Ruth) last in a weak lineup.

Life requires nitrogen that has been "fixed" through combination

with other elements. Thermodynamics imposes a constraint on all possible methods of fixation:invariably energy must be supplied

by David R. Safrany

itrogen is one of the major con less by the ingenuity of the chemist in potential energy decreases and is con·· N stituent elements of life; it is an discovering novel reactions than by ther verted to kinetic energy, or motion. essential material in the construc modynamic constraints that apply to all When the car reaches ground level, its tion of proteins and other biological possible methods of nitrogen fixation. potential energy is exhausted. molecules. Nitrogen is also the major Nitrogen is useful to life only in fixed Similarly, in a chemical reaction free component of the atmosphere: dry air form because nitrogen as it is found in energy decreases and is converted to consists of about 79 percent nitrogen. the air, as a diatomic gas (N2), is nearly kinetic energy, which is manifested as The abundance of the element does not inert. In order to make it combine with ensure its biological availability, how other substances an irreducible quantity ever, because nitrogen can be incor of energy must be added to the system. SOLAR ENERGY porated into most living systems only in This energy cost can be paid in any of "fixed" form, that is, only when it is com several currencies, through an energy bined with certain other elements. rich raw material, for example, or direct The natural supply of fixednitrogen ly as thermal or electrical energy, but it ATMOSPHERE is limited, and it imposes a limit on the must be paid. For this reason any large capacity of world agriculture. Supple reduction in the cost of fixed nitrogen is mental nitrogen must be provided by likely to result not from improvements chemical fertilizers containing nitrogen in the technology of fixation itself, which 02 N2 fixed by industrial methods, chiefly the is already highly developed, but from ad Haber process, in which nitrogen is com vances in the technologies that supply bined with hydrogen to form ammonia. the energy or raw materials needed for NITROGEN OXIDE In 1972 more than 14 million tons of am fixation. r-+ PROCESSES monia were manufactured in the U.S., r and production is doubling about every Free Ene gy five years. The demand will continue to grow as the world population increases, THERMAL, Thermodynamics is the science that NUCLEAR OR and in particular as the techniques of enables one to calculate the energy ab ELECTRICAL �O,- NITRATE modern agriculture, which include the sorbed or dissipated by the reactants ENERGY CONVERSION � intensive application of nitrogenous fer during a chemical process, and thereby tilizers, are introduced in the underde to determine whether or not a process is veloped regions of the world. possible under given conditions. A fun

Among industrial chemical processes damental concept in thermodynamics is N02-. NO,- the Haber process is remarkably efficient, the concept of "free energy," an intrinsic and its product is comparatively inex property of substances expressed in kilo pensive. Until the "energy crisis" of the calories per mole. (A mole is the equiva SOIL past year the manufacturing cost of am lent in grams of the molecular weight of monia was stable at slightly more than a substance.) In a chemical reaction the one cent per pound. Because of the enor change in free energy, denoted �F, can mous quantity of fixed nitrogen con be calculated simply by subtracting the sumed, however, and because most of sum of the free energies of the reactants it contributes to the production of a ba from that of the products. N02- , NO,- sic commodity (food) a price reduction An analogy can be made between free would have important and widespread energy and gravitational potential en consequences. During the past 60 years ergy, as exemplified by the physics of a NITROGEN CYCLE describes a continuous numerous alternatives to the Haber proc roller coaster. The roller coaster car at intercbange of the element between the at ess have been proposed. The commercial the top of the highest hill has maximum mosphere and living organisms. In broad success of such proposals is determined potential energy; as it rolls downhill its outline, the molecular gas (N2) is converted

© 1974 SCIENTIFIC AMERICAN, INC heat, until the system reaches thermo per mole of hydrogen consumed or wa gen is stable and, if it is left alone, the dynamic equilibrium, the point of low ter produced. Thermodynamics predicts gases will not combine; they explode to est free energy for that system. The ref that the reverse reaction, in which water form water only when the reaction is erence level from which free energy breaks down into hydrogen and oxygen, initiated by a small input of energy, such is measured-the equivalent of ground can occur only when 57 kilocalories per as that provided by an electric spark. level for the roller coaster-is generally mole is supplied to the system. The pre The energy required to initiate an exo set arbitrarily at the free-energy level of diction is confirmed by the common ergic reaction is called the energy of the stable forms of the elements involved place observation that water never ex activation. in a reaction at some specified tempera plodes into its component gases. Just as thermodynamics cannot pre ture, usually 25 degrees Celsius. In other Although thermodynamics is a pow dict whether or not an exoergic reaction words, the free energy of a substance in erful instrument for analysis, it cannot will proceed, it cannot predict what its equilibrium form at room temperature tell us all we might want to know about path the reaction will take if it does pro is set equal to zero. Calculated values of the behavior of chemical systems. Ther ceed. Change in free energy is calcu tJ.F therefore indicate the tendency of modynamics predicts with certainty, for lated from the properties of the reactants the reactants to revert to their stable example, that without an external source and products alone; there may be any form. of energy an endoergic reaction will not number of intermediate products and Reactions that proceed with a de take place; predictions about exoergic dozens of possible mechanisms relating crease in free energy (that is, where tJ.F reactions cannot be made with the same them, but thermodynamics cannot tell is negative) are called exoergic reactions. certainty. A calculated decrease in free us anything about them. Activation en Because all chemical processes are re energy indicates only that a postulated ergy and the paths of chemical reactions versible there is for every exoergic reac reaction is possible, not that it will ac are outside the province of thermody tion a corresponding endoergic one, in tually occur. As we have seen, in the re namics; they are the subject of the field which free energy must be supplied. Hy action of gaseous hydrogen and oxygen of study called chemical kinetics. drogen and oxygen, for example, com tJ.F is -57 kilocalories, indicating that In spite of these limitations, thermo bine exoergically to form water; the de the reaction is strongly exoergic. Never dynamics provides a valuable framework crease in free energy is 57 kilocalories theless, a mixture of hydrogen and oxy- for evaluating possible chemical proc-

SOLAR EN ERGY

(N2, 02, CO2 AND OTHER GAS ES)

N2, 02 N 2 C02, H20

HABER AND ORGANIC WASTES AND DEAD ORGANIC MAT ERIAL OTHER ANIMALS N2 AMMONIA PROCESSES

J 1 AMINOAC IDS PROTEINS H2 � V r IJH, l

NITROGEN· OTHER l t , FIXING PLANTS WASTES AND PLANTS I FOSS IL FUELS I DEAD ORGANISMS

N02-, NO,- AMNOI AC IDS NH4+ 1 AMMONIFYING BACTERIA NH4+ ) NITRIFYING BACTERIA NH�+ DENITRIFYING NO,- NO,- BACTERIA N2

tain energy directly from sunlight ; solar energy, accumulated in into fixed forms (NH4 + , N02 -, NO� -); these are then degraded and returned to the atmosphere hy the concerted action of several fossil fuels, also drives the synthesis of ammonia by the Haber kinds of bacteria. All methods of fixation require a source of en process. The nitrogen oxide processes, which are not now commer cially competitive, require thermal, electrical or nuclear energy. ergy (heavy lines). Nitrogen.fixing plants (such as the legumes) ob·

RE-FORMING some processes that initially appear NATU RAL GAS � promising from thermodynamic consid CH. + H,O--;. erations may prove unattractive for STEAM � CO + 3H, kinetic reasons, any process that is for bidden by thermodynamics must be im mediately excluded from consideration, since no manipulation of chemical ki H, netics can alter the fundamental free co 1 energy transactions.

UREA The Haber Process SHIFTING CONVERSION CO, The ultimate use of most industrial STEAM � CO + H, O--;. 2NHJ + CO, � fixed nitrogen today is fertilizer, but a NHJ CO(NH,), + H,O CO, + H, major part of the production of the ear liest Haber fixation plants was diverted to a much different purpose: the manu facture of munitions, most of which are H, J based on nitrate compounds. Earlier sup plies of fixednitrogen were obtained NITRATE largely from Chilean deposits of saltpeter AMMONIA CONVERSION (sodium nitrate) and from various chemi SYNTHESIS NHJ NHJ + 20,� cal methods, all of them inefficient, that AIR N, + 3H, --;. � H� HNOJ + H,O produce carbon-nitrogen compounds 2NHJ (cyanides). The introduction of synthetic HNOJ + NHJ--;' ammonia just before World War I is con NH.NOJ sidered to have had a significant effect on the prosecution of that war. In the long NHJ �, NH.NOJ CO(NH,), run, however, the agricultural uses of (AMMONIA) (AMMONIUM NITRATE) (UREA) fixed nitrogen have proved much more

HABER PROCESS is the catalytic synthesis of ammonia. Hydrogen is derived from meth important than munitions and all other ane by the re-forming and shifting reactions and then combined with nitrogen at high uses. temperature and pressure in the presence of a catalyst. The ammonia can be utilized direct· Plant growth demands large quanti Iy or it can be couverted to nitrate or urea, two common fertilizers. The Haber process, de ties of fixednitrogen, most of which is veloped 60 years ago, today accounts for virtually all industrial fixed.nitrogen production. , incorporated into proteins and other bio logical molecules and becomes available to animals in the form of food. Subse quently the nitrogen is returned to the MOLECULE ION IN AQUEOUS SOLUTION soil in organic wastes and dead orga SUBSTANCE nisms, and eventually it is returned to FORMULA STRUCTURE NAME FORMULA STRUCTURE the atmosphere, thus forming a closed cycle [see illustration on preceding two MOLECULAR N, N'" N pages]. NITROGEN ------The high-yield crops of modern agri culture can quickly deplete the soil of H AMMONIUM fixed nitrogen. The supply can be re AMMONIA NHJ I NH4+ N ION / "- plenished by applying organic fertilizers, H H ["-H' such as mulch or manure, but the nitro gen content of these substances is not NITRIC NITRITE N NO N"' O NO,' high. Another method is the growing of OXIDE ION � 0 ""-0' legumes such as beans, peas, alfalfa and clover, which are exempt from the gen 0 N. NITROGEN NITRATE eral dependency of plants on fixed forms NO, . ION NOJ' DIOXIDE � ,,- �+ of nitrogen because they are able to uti 0 0 / ""- , 0 0 , lize atmospheric nitrogen directly. The legumes fix nitrogen with the aid of bac teria that live symbiotically in nodules in MOLECULAR SPECIES important in the nitrogen cycle are compounds of nitrogen with their roots. Although the magnitude of hydrogen or oxygen. The triple bond in molecular nitrogen is in part responsible for the stability of the molecule. Ammonia is the product of the Haber process, of some other po biological fixation is difficult to measure, tential industrial methods and apparently of biological fixation as well ; the nitrogen oxides it appears likely that the activities of the would he formed in other proposed processes. The three dots in the NO and NO? struc· legumes and their symbionts, and of cer ttlral diagrams represent three-electron bon ds. Fixed nitrogen is absorbed by plants only tain algae and free-living bacteria, make in ionized form ; one ion can be converted to another by industrial methods and by bacteria. the largest contribution to the world ni-

RE-FORMING NH

> (9 a: w N, + 2N H3 z 3H, � w PHOTOSYNTHESIS w SOLAR SHIFTING w CO, + H,O ----?CARBOHYDRA TES a: CO + H,O CO, + H, u.. ENERGY �

EQUILIBRIUM (CO,. H,O. N, )

THERMODYNAMIC ANALYSIS of the Haber process relies on with a modest decrease in free energy, but the overall process is . the concept of "free energy," an intrinsic property of substances strongly endoergic. It begins with the photosynthesis of carbohy that determines their potential for combining with other elements. drates in green plants, promoted by light quanta from the sun. The When free energy increases (t he change in free energy is denoted carbohydrates decay exoergically to form fossil fuels such as meth �F), energy must be supplied to the system and the reaction is ane (CH4), which can then be re-formed endoergically to yield hy called an endoergic one ; when a reaction is exoergic, on the other drogen gas. Additional hydrogen is liberated in the shifting reac hand, free energy decreases and is dissipated as heat. The ammonia tion. Much of the free energy of the products of photosynthesis thus synthesis that is the ultimate event in the Haber process proceeds resides in hydrogen and is available to promote ammonia synthesis.

trogen cycle [see "The Nitrogen Cycle," catalysts are sophisticated and highly nitrogen is most abundant on the earth by C. C. Delwiche; SCIENTIFIC AMERI efficient, and their use has become rou as a molecular gas rather than in some CAN, September, 1970]. tine. Historically, however, the develop other form, such as ammonia. (Nitric The most efficient way to replenish ment of catalysts was a formidable task. acid could be considered an alternative soil nitrogen is through the application Haber's chief contribution to the tech equilibrium state, but it can be ignored of chemical fertilizers, in which nitrogen nology of nitrogen fixation was the dis because kinetic considerations inhibit its is a major component. The nitrogen can covery of a catalyst suitable for com formation.) Nitrogen gas is thus very be supplied as anhydrous ammonia, as mercial production, and it was for this near a condition of minimum free energy the ammonium ion (NH4 +) or as the ni achievement that he received a Nobel and has almost no potential for combin trate ion (NOs -). In some cases both prize in 1918. ing with other elements. In this fact is ions are supplied, in the form of ammo The Haber process is exoergic: 6F is the crux of the nitrogen-fixation problem: nium nitrate (NH4NOs). Another com -9 kilocalories. In other words, the sum because nitrogen gas is at equilibrium or mon vehicle for fixed nitrogen, urea, has of the free energies of N 2 and H2 exceeds near it free energy must be supplied in the formula CO(NH2)2 [see bottom illus the free energy of NHs by nine kilocalo order to form nitrogen compounds. tration on opposite page]. All these prod ries, which must be diSSipated during If nitrogen is at equilibrium, then in ucts can be manufactured from am the reaction as heat. This simple energy the Haber process free energy must be monia, and ammonia is therefore the equation misrepresents the thermody brought to the reaction by the other raw primary raw material of the nitrogenous namics of nitrogen fixation, however, be material: hydrogen. Hydrogen gas is in fertilizer industry. cause it embraces only one part of the fact rich in free energy; its equilibrium The first efficient synthesis of ammo overall chemical system that culminates state under terrestrial conditions is not nia directly from its component elements in the synthesis of ammonia. In order to the molecular gas but water. The source was achieved by Fritz Haber in Germany grasp the extent of the misrepresentation of this free energy is apparent from the in 1909; the first commercial plant, de one must consider the source of the raw origin of commercial hydrogen; it is de signed by Haber and Karl Bosch, began materials consumed in the process, and rived from fossil fuels. operating in 1913. In the Haber process in particular the contribution each makes Coal, oil and natural gas were formed one molecule of nitrogen (N2) and three to the sum of the free energies of the from dead organic matter; in the con molecules of hydrogen (H2) combine at reactants. text of this discussion it is sufficient to elevated temperature and pressure and The diatomic gas is the equilibrium assume that they were formed from one class of organic substances, the carbohy in the presence of a catalyst to form two state of nitrogen under terrestrial condi molecules of ammonia (NHs). Modern tions; it is for this reason, in fact, that drates, compounds whose composition is

© 1974 SCIENTIFIC AMERICAN, INC some multiple of the empirical formula but b.F is only -54 kilocalories, so that forming, and since shifting dissipa tes CH20. Carbohydrates are the direct not all the initial free energy of the car only seven kilocalories, the hydrogen product of the photosynthetic activity of bohydrates is released. Neither is any produced by these reactions must retain green plants, in which carbon dioxide substantial portion carried off by the a substantial part of the free energy ini (C02) reacts (indirectly) with water. Just CO2; therefore of 93 kilocalories per tially present in the methane of natural as water is the equilibrium form of hy mole of free energy embodied in plant gas. drogen, carbon dioxide is the equilibrium carbohydrates 39 kilocalories are re The free energy inherent in hydrogen form of carbon under terrestrial condi tained by the methane of natural gas. gas is the driving force of the Haber tions, and both reactants have minimal In the U.S. methane is the customary process; indeed, the series of reactions free energy. The overall photosynthetic commercial source of hydrogen. In the that liberates hydrogen is an essential process must therefore be highly en process called re-forming it is treated complement to the reaction that takes doergic: 6F is + 125 kilocalories per with high-temperature steam, producing place during ammonia synthesis. It is the mole. As is well known, the energy need carbon monoxide (CO) and molecular endoergic photosynthesis of carbohy ed to promote this reaction is provided hydrogen. The reaction is endoergic drates on which the exoergic reaction of by light quanta from the sun. About (b.F= +34 kilocalories), the required nitrogen and hydrogen ultimately de three-fourths of the energy supplied, 93 free energy being proVided in thermal pends. The sum of all these reactions is kilocalories, resides in the carbohydrate form by the steam. In a subsequent proc included in what can be called the over product and is available as free energy to ess, called shifting, the mixture of car all Haber process [see illustration on pre drive subsequent exoergic reactions. bon monoxide and hydrogen is reacted ceding page]. One of these subsequent reactions is with additional steam to generate car Hydrogen not only provides the en the degradation of carbohydrates to bon dioxide and more hydrogen. This ergy for the Haber process; it also de hydrocarbons (compounds composed of reaction is exoergic, with a decrease in termines its cost. In fact, it is indicative carbon and hydrogen only) during the free energy of seven kilocalories [s ee top of the efficiency of the Haber process formation of natural gas and petroleum. illustration on page 66]. that the cost of ammonia is almost en One such reaction is the transformation As in the decomposition of carbo tirely the cost of the hydrogen consumed of carbohydrates into methane (CH4), hydrates, carbon dioxide removes only in making it. Until recent months the the simplest hydrocarbon and the princi negligible free energy from the system, price of hydrogen had been stable for pal constituent of natural gas. The de because it is near equilibrium. Since an decades at from six to seven cents per composition, which evolves carbon di additional 34 kilocalories of free energy pound; ammonia is about a sixth hydro oxide as well as methane, is exoergic, is supplied to the methane during re- gen by weight, and until recently it could be made for a little more than one cent per pound. Even at that cost the volume of am monia production has provided strong motivation to those seeking cheaper methods of nitrogen fixation. As the METABOLIC DITHIONIT E OR PROCESSES PYRUVATE, ATP prices of petroleum and natural gas in \ crease, the endeavor is certain to become more urgent, since the prices of hydro gen and ammonia must rise along with PHOTOSYNTH ESIS them. Several of these proposed methods SOLAR CO, + H2 0 CARBOHYDRATES are intended to replace hydrogen with � HFE ENERGY �' some less expensive substance that might NITROGENASE N�" N' + N, react conveniently with atmospheric ni

> trogen; others would retain hydrogen as (!l a: a reactant in the hope that the develop w HFE NITROGENASE z ment of a much improved catalyst would w REDUCTION w eliminate the need for high temperature w HFE NITROGENASE. N, � NH, a: and pressure. In the latter category are u. I, possible methods fashioned by analogy \\ to the mechanisms presumed to operate in those living organisms capable of fix ing atmospheric nitrogen.

I Biological Fixation

The activities of nitrogen-fixingor ganisms have been known for more than 100 years and have been intensively EXTRACTS FROM BACTERIA of the genera and fix nitrogen Azotobacter Clostridium studied for decades. The details of the in vitro. One possible thermodynamic model of the mechanism of this fixation process is diagrammed. A series of metabolic reactions, whose nature is unknown, generates a nitro· biochemical mechanism of fixation nev genase, an enzyme that promotes reactions of nitrogen high in free energy (HFE nitro ertheless remain obscure. It has been genase). The HFE nitrogenase combines with atmospheric nitrogen, and the resulting com· known for some time that trace amounts plex is reduced to yield ammonia. Fixation takes place only in the presence of a strong re of iron and calcium, and somewhat more ductant, such as dithionite or pyruvate ; adenosine triphosphate (ATP) is also required. molybdenum, are required by all bio-

© 1974 SCIENTIFIC AMERICAN, INC logical fixation systems and that large amounts of carbohydrates are invariably consumed during the synthesis of a rela tively small amount of fixed nitrogen. \ METABOLIC Furthermore, two kinds of enzyme have PROCESSES DITHIONI TE, AT P been found to be present in all nitrogen fixing organisms: a nitrogenase and a hy PHOTOSYNTHESIS drogenase, which respectively promote SOLAR reactions of nitrogen and hydrogen. The C02 + H20 --7 CARBOHYDRATES presence of a hydrogenase is particularly EN RGY intriguing in that it suggests that ammo nia or some other compound involving > (9 nitrogen-hydrogen bonds is the product II: NIT ROGENASE. ATP W of the synthesis. Z W Until 1960 all studies of biological fix W W ation had to be made in the organisms II: LL themselves in vivo. In that year J. E. Car nahan, John E. Castle, Leonard E. Mor I, tenson and Howard F. Mower of E. I. du Pont de Nemours & Co. isolated an ex tract from the anaerobic bacterium Clos tridium pasteurianum that fixes nitrogen I in vitro. The extract was found to be ac tive in the presence of sodium pyruvate, EQUILIBRIUM (N2. CO ,. H2 0) a substance closely related to pyruvic acid, which participates in certain meta bolic cycles. As in the case of the car ALTERNATIVE MODEL of nitrogen fixation by extracts from bacteria postulates a "by· bohydrate consumed during fixation in drogen·active species" (HAS) capable of reacting directly with molecular nitrogen. Are· vivo, large quantities of pyruvate were ducing agent and ATP are still required, but in this interpretation of the experimental reo required to fix only a little nitrogen. sults the free energy that must be supplied to the system comes not from the nitrogenase Two possible functions were suggest but from the hydrogen.active species. The nitrogenase serves merely as a catalyst, promot· ed for the pyruvate: it might serve as ing the reaction at room temperature; the id entity of the hypothetical HAS is unknown. a source of hydrogen and it might ef fect fixation through the involvement of adenosine triphosphate (ATP), the sub of A TP were required for fixation [see ponents of the nitrogenases, or they may stance that participates in almost all bio illustrations on these two pages]. be other substances as yet undiscovered. logical energy transactions. It was sub These investigations provide only an It is equally plausible from the point of sequently discovered that the reaction inadequate description of the mechanism view of thermodynamics that the active proceeds in the absence of pyruvate if of biological fixation, but they do enable agent is molecular hydrogen itself, or molecular hydrogen is supplied and if us to construct possible thermodynamic perhaps some postulated "hydrogen-ac ATP is present in small amounts. The models. The ultimate reactants must be tive species" whose reaction with nitro Clostridium extract could be separated carbon dioxide, water and atmospheric gen is catalyzed by a nitrogenase and into two fractions, one that metabolized nitrogen, and the primary product is ap promoted by ATP. The fact that pyru pyruvate and one that participated in the parently ammonia. The thermodynamic vate and dithionite reduce nitrogen to actual fixation process. The latter frac similarity of the system to the overall ammonia in laboratory extracts by no tion could be further separated into two Haber process is unmistakable. In both means proves that similar strong reduc constituents, one containing iron and the processes the first step is the endoergic ing agents participate in the natural other iron and molybdenum. photosynthesis of carbohydrates. In the process. Thus the behavior of the system Another experimental system, an ex Haber process various transformations, as it is now known can be described by tract of the aerobic bacterium Azotobac mainly exoergic, convert carbohydrates more than one thermodynamic model, ter vinelandii, was later studied by Wil to hydrogen that is rich in free energy, and additional information from kinetic liam A. Bulen and Richard C. Burns of which then reacts exoergically with ni studies is required in order to choose be the Charles F. Kettering Research Lab trogen. In the biological system, al tween alternative explanations. oratory. In this case pyruvate could be though the reaction path is unknown, it One other puzzle of biological fixation replaced by sodium dithionite (Na2S204), is certain that exoergic processes ulti is at least approachable through thermo a powerful reducing agent, or donor of mately derived from carbohydrates must dynamics, even if any proposed answers electrons. Dithionite was soon found to produce 'one or more substances of high must for now remain somewhat specula be active with the Clostridium extract as free energy capable of combining with tive. The puzzle is why the process seems well, and reduction by dithionite has molecular nitrogen. to be so inefficient,why so much carbo since become a standard test for nitro The salient mystery in biological fixa hydrate must be consumed to produce a gen-fixing activity. The Azotobacter ex tion is the identity of these high-free little fixed nitrogen. A reasonable expla tract could also be divided into two frac energy substances. It is a mystery that nation is that not all the free energy of tions, one containing iron and the other thermodynamics cannot solve. The sub the carbohydrates is directed to the syn iron and molybdenum. In addition, as in stances may be the iron-containing or the thesis of ammonia. In biological systems the earlier experiments small quantities iron-and-molybdenum-containing com- competing reactions are common, and in

© 1974 SCIENTIFIC AMERICAN, INC this case there is reason to believe the hy ess requires. Several groups of investiga ploy not pure metals but metallo-organic drogenase reactions that lead to nitrogen tors in the U.S., Canada and the U.S.S.R. compounds containing titanium or one of fixation would show a greater tendency have recently reported the discovery of a few other metals. An important point to convert carbohydrates to carbon di reactions in which this goal seems to is that titanium is one of the group of oxide and water than to convert them to have been achieved. elements called the transition metals, and the precursors of ammonia. Fixed nitro Nitrogen fixation under ambient con so are the iron and molybdenum found in gen might even be a by-product of a ditions is not in itself novel. In one long nitrogenases. process whose primary function is unre recognized mechanism metallic lithium The titanium compounds were first lated to nitrogen metabolism. combines with atmospheric nitrogen at synthesized by Eugene E. van Tamelen room temperature to form lithium ni and his colleagues at Stanford Univer Metallo-Organic Complexes tride (LiaN). Ammonia can be produced sity. One of the compounds, titanium by reacting lithium nitride with water, diisopropoxide, consists of two propyl An interesting approach to under yielding as a by-product lithium hydrox groups-chains of three carbon atoms standing biological nitrogen fixation is ide (LiOH). The lithium hydroxide will bonded to a titanium atom through oxy through constructing non biological sys react further with hydrochloric acid to gen atoms connected with the center tems that seem to imitate the perform form lithium chloride. Each of these re carbon of each propyl chain. For brevity ance of the living cell. A catalyst capable actions is exoergic, but they proceed only the molecule can be designated Ti(OR)2, of promoting the reaction of nitrogen and at the cost of dissipating the high free where OR rep �sents the isopropoxide hydrogen at room temperature and pres energy of metallic lithium. If ammonia radical. sure, for example, might help to illumi is to be produced continuously by this Ti(ORh combines with molecular ni nate the nature and mechanism of the method, lithium must be regenerated trogen at room temperature to form the enzymes found in Clostridium and Azo from the chloride by electrolysis, an en complex Ti(ORh·N2. Sodium naphtha tobacter. There is another motive for de doergic process that consumes as much lide, a strong reducing agent denoted veloping such catalysts: they might make energy as the preceding reactions liber NaNp, reduces the complex to a nitride it possible to synthesize ammonia under ate [see illustration below]. whose character has not been determined milder conditions than the Haber proc- The recently reported reactions em- and that is therefore denoted simply [re duced Ti(OR)2'N2]' Ammonia is evolved when [reduced Ti(ORh'N2] is reacted with isopropyl alcohol, and simulta neously the Ti(OR)2 is converted to Ti(OR)4' Ammonia continues to be formed as long as NaNp is added to the

6Li + N2 2LiJN system; alternatively metallic sodium can � = -210 KCA L. AF be added, since it combines exoergically with naphthalene liberated in the last stage of the reaction to regenerate NaNp. The NaNp is needed to restore Ti(OR)4

AF = + 330 KCAL. to the form of Ti(OR)2' This series of reactions is much more complex than that employed in fixation HYDROLYSIS with metallic lithium, but its principle > of operation is identical. All the reactions (!) ELECTROLYSIS a:: UJ ELECTRICAL described are exoergic, but if the process z UJ 6LiC I � 6Li + 3CI2 is to operate continuously, metallic so UJ ENERGY UJ dium must be regenerated by electroly a:: l1. sis, an endoergic step. In both methods it is electrical energy from outside the chemical system, and not energy inher ent in the reactants, that provides the free energy for fixation [see illustration on page 75]. Thus it does not appear that a new class of catalysts has actually been discovered. The metallo-organic process is at least superficially similar to biological fixation. EQUILIBRIUM (N2. LiC I ) In both cases the reactions proceed at room temperature, and both employ compounds containing transition metals. LITHIUM AND NITROGEN combine to form lithium nitride (LiaN ) in a reaction that In addition both the extracts from bio proceeds exoergically at room temperature and pressure. Fr om this primary fixation prod· logical systems and the metallo-organic uct ammonia can be generated by reacting the nitride with water, producing as a by. complexes can operate with strong re product lithium hydroxide (LiOH). Fixation by this method is thermodynamically permis· sible because lithium, like hydrogen, is high in free energy; if ammonia is to be produced ducing agents. C!ontinuously, however, the high·free.energy lithium must be regenerated. This is ac· On the other hand, biological systems complished by converting the hyd roxide to the chloride, then decomposing the chloride in vitro are capable of fixing nitro ' by electrolysis. The regeneration is endoergic and requires 330 kiloca lories per mole. gen with molecular hydrogen as well as

Solve problems like these in seconds: ' sin 12° 45 9" 1T • e"2

• 4.561.23 log 2.3

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© 1974 SCIENTIFIC AMERICAN, INC with dithionite and other strong reduc self would proceed through a relatively obtained directly from the atmosphere ing agents, whereas the metallo-organic simple mechanism analogous to the Ha without cost. Unfortunately they cannot processes have not been operated with ber process [see illustrations on next two be induced to combine without the ex hydrogen. Moreover, there is reason to pagesl. There is an obvious objection to penditure of a large amount of energy. doubt that reagents as powerful as di this hypothesis too, however: no reac Unlike hydrogen, oxygen has insufficient thionite or sodium naphthalide could be tions at low temperature between nitro free energy to react with nitrogen under tolerated inside the cell. Finally, evi gen and an appropriate hydrogen-active ordinary conditions; neither element is dence from the metallo-organic process species have yet been observed. The res sufficiently far above its equilibrium suggests that in such systems nitrogen olution of the issue will have to await state. The formation of nitric oxide is en fixation proceeds only with a very large further study of biological fixation sys doergic; ilF is +41 kilocalories, and this change in free energy, necessarily in tems. quantity of energy must be supplied cluding a large input of free energy to from an external source. The methods by overcome an endoergic step. It seems Oxidative Methods which the required free energy can be doubtful that carbohydrate metabolism supplied fall into two categories: activa could provide the required free energy. The fixation techniques discussed tion by heating and low-temperature ac Any analogy between the metallo-or above have all involved the reduction of tivation by ionization. ganic process and biological fixation im nitrogen to form ammonia. There are Thermal activation is accomplished by plies that the final reactant in the biologi also oxidative processes in which the heating air to a temperature of from cal system, the substanc G hat actually products are nitrogen oxides. These in 2,000 to 3,000 degrees C. in a furnace. It combines with nitrogen, is a metal-con clude several compounds, such as nitric is often achieved unintentionally in fos taining component of a nitrogenase. The oxide (NO), nitrogen dioxide (N02), ni sil-fuel power plants and internal-com high energy cost of regenerating such trogen trioxide (N20a) and nitrogen bustion engines, producing air pollution molecules suggests instead that the ni tetroxide (N204), that tend to be formed in the form of a brown haze of nitrogen trogenase may be a more typical enzyme together. It is convenient to speak of the dioxide. Thermal activation was also the that does not require an external source mixture as if it consisted entirely of nitric basis of two industrial methods of fixa of energy for regeneration and that the oxide. tion, both of which are now obsolete. In ultimate reactant is a hydrogen-active The potential attraction of such com the Wisconsin process the combustion of species. In that case the reactant would pounds should be immediately apparent: fossil fuels provided the necessary heat, not have to be regenerated; fixation it- both raw materials can be conveniently whereas electrical energy was employed

Na + Np � NaNp + V,H, \� �F = +3 60 KCAl. , NITROGEN FIX ATION Ti(OR» + N, � Ti(OR» . N, \� ELECTROLYSIS , ELECTRICAL > REDUCTION Cl 6NaCI � 6N a + 3CI, a: " , "'" --s',. " "(OR), . w ENERGY z w w w a: u. ALCOHOLYSIS

• -C REDUCED Ti(OR), N, + 6ROH """"'OR)'

REGENERATION Ti(OR). + 2NaNp \� 2Na: + 2Np + Ti (OR» CHL ORINATION 6 NaOR + 6 HCI ----7� 6NaCI + 6 ROH EQUILIBRIUM (N,. NaCI )

METALLO·ORGANIC COMPLEXES, such as titanium diisopro· energy and cannot combine with nitrogen. Ti (OR)2 is regenerated poxide [Ti(OR)2]' also fixnitrogen under ambient conditions. In by reaction with additional sodium naphthalide. If ammonia syn a procedure developed by Eugene E. van Tamelen, Ti(OR)2' which thesis is to be continuous, sodium naphthalide must be regenerated is rich in free energy. combines with nitrogen and is then reduced from metallic sodium, produced by the electrol ysis of sodium by sodium naphthalide (NaNp ) to a compound whose nature is un chloride at an energy cost of 360 kilocalories per mole. A similarity known and that is therefore designated [reduced Ti(OR)2·N2]. has been suggested between the metallo·organic complexes and the Treatment with isopropyl alcohol (R OH) liberates ammonia as nitrogenases of biological systems. in part because both contain well as free naphthalene and sodi um propoxide (NaOR); at the transition metals. An equally cogent analogy can be made between same time Ti(OR) 2 is converted to Ti(OR)4' which has little free fixation by the metallo·organic compounds and fixation by lithium.

75 © 1974 SCIENTIFIC AMERICAN, INC in the Birkeland-Eyde "flaming arc" ency for nitrogen and oxygen to associ volts, so that a low-temperature dis process. ate in NO molecules. charge is initiated, or by exposing air to At high temperature the average ve The efficiencyof thermal activation is an intense flux of ionizing radiation in locity of gas molecules increases, and so low, however. The collision processes side a nuclear reactor. In either case the do the frequency and violence of col that lead to activation are reversible, gas molecules are bombarded by fast lisions between molecules. When the and excited molecules can relinquish moving ions and the collisions are in velocity becomes high enough, some their free energy through collisions with elastic. The resulting cascade of reac molecules no longer rebound from one molecules that have not been excited; tions can produce a substantial yield of another elastically but convert some of at temperatures that are commercially nitrogen oxides. their kinetic energy into the free energy practical the latter are always in the ma As in all endoergic processes, the tell of excitation or ionization. If the stable jority and excited molecules rapidly lose ing factor in calculating the feasibility configuration of the electrons in the their energy. A dynamic balance is of low-temperature activation is the cost molecule is disrupted, or if the normal reached between activation and deac of energy. If the source of energy is elec molecular vibrations and rotations are tivation, with the result that at 2,200 de tricity, its cost would seem to forbid fix intensified, the molecule enters an ex grees C. only about 2 percent of the mix ation by air activation as a commercial cited state; if an electron is dislodged ture is converted to nitric oxide. Because enterprise. The "chemonuclear" tech altogether, the molecule becomes an all the air must be heated, and not just nique, on the other hand, utilizes a re ion, bearing a positive charge. Excited the small fraction that contributes to the markably cheap form of energy: the molecules and ions possess very high free formation of the product, the process re kinetic energy of the nuclear fragments energy; the N2 + ion, for example, has a quires about 20 times the minimum theo produced by the fission of a uranium free energy of 358 kilocalories. As a con retical energy requirement of 41 kilo nucleus. The pioneering work in this sequence they readily enter into many calories per mole. Most of the energy field has been done by Paul Harteck and chemical combinations, and the products goes into heating the bulk gas instead of his colleagues at Rensselaer Polytechnic of these combinations often retain suffi into promoting the desired reactions. Institute and the Brookhaven National cient free energy to support further re Low-temperature ionization has the Laboratory. They have found that spe actions [see illustration on page 78 ]. At Significant advantage that in principle cial reactor designs are required to en high temperature nitric oxide represents all the molecules of the gas can be ion sure that a large proportion of the fission a state of lower free energy than the ex ized or excited. The activation can be fragments escape into the gas ; their cited and ionized component elements accomplished by subjecting the air to many elegant experiments have shown, do, and as a result there is a strong tend- an electric potential of a few thousand however, that with the proper design

METABOLIC PROCESSES ( ATP \ I � \ REDUCT) ANT \'--- HFE NITROGENAS I HFE NITROGENASE + N NITRIDE � 2 \ ---?�

PHOTOSYr INTHE / SOLAR ts' C02 + H20 ---? CARBOHYDRATES ENERGY ( � N''''O' . "'0 ""''''' Rm"cm R'O' . ~ \ > C) \ a: w I z w REGENERATION w LFE NITROGENASE w I � a: HFE NITROGENASE REDUCED NITRIDE NH3 + LFE NITROGENASE u. ---? I \�\�� I

BIOLOGICAL NITROGEN FIXATION can be described by either acts with an enzyme of high free energy (HFE nitrogenase). The reo of two thermodynamic models; studies of fixation by bacterial ex· sulting nitride is reduced and exoergically yields ammonia, the en· tracts in vitro and by metallo.organic complexes have not yet pro· zyme being converted to a low.free.energy (LFE) form. Three series vided the means to discriminate between them. In one model (left), of couple reactions are required by the model: one to produce the constructed by analogy to the metallo·organic systems, nitrogen reo HFE nitrogenase, one to produce the redu ctant and one to convert

© 1974 SCIENTIFIC AMERICAN, INC more than half of the fissionenergy can tive fixation methods therefore depends tive costs of the various methods of nitro be made available to promote chemical ultimately on how energy is supplied in gen fixation can be calculated. Hydrogen reactions. The chemonuclear process the endoergic step. The solar energy for the Haber process and thermal and thus has the potential of high energy latent in carbohydrates and other organ electrical energy for other methods de conversion efficiency. Whether or not it ic matter can be employed, as it is in the rive for the most part from the same can become a practical method of nitro Haber process, but only at a high cost source-fossil fuels-and any increase in gen fixation depends on economic and in raw materials. Alternatively the free fuel costs will raise the cost of each meth technologiCal considerations. resources of the air can be tapped, but od proportionately. For this reason it will only when an external source of thermal, suffice to discuss the costs of fixation in The Economics of Fixation electrical or nuclear energy is provided. terms of the prices that prevailed before For any fixation process the theoreti the "energy crisis" began. The several methods of fixationI cal minimum energy requirement can be Economic analysis and the history of have been discussing employ a variety of calculated directly from thermodynamic the nitrogen-fixationindustry both sug raw materials, sources of energy and re information. Estimating the cost of this gest that if fossil fuels are to be employed action processes; superficially they seem energy, however, has recently become a in fixation, then the Haber process is the to be hardly related at all. They can nev difficult exercise in prognostication. The most efficient way to utilize them. When ertheless be conveniently and accurately prices of petroleum and natural gas are hydrogen cost six to seven cents per compared, since the same thermody influenced by many political, economic pound (and ammonia could therefore be namic laws govern them all. In fact, from and technological factors, and even for made by the Haber process for slightly the point of view of thermodynamics all the immediate future they cannot be re more than one cent per pound), thermal the processes have a similar overall form. liably predicted. The most that can be energy cost about .1 cent per kilowatt In each case energy is expended in pre said is that the price will eventually be hour and electrical energy, also largely liminary endoergic reactions that yield stabilized again, since continued price derived from fossil fuels, cost about .8 substances high in free energy; these increases will make practical the recov cent per kilowatt-hour. At these prices then react exoergically in the fixation ery of otherwise unprofitable reserves, the metallo-organic system, which re process itself. It can even be predicted such as shale oil. The level at which sta quires 5.7 kilowatt-hours of electricity with certainty that any as yet undiscov bility will be achieved is for now un for each pound of ammonia produced, ered fixation systems will conform to the known. would yield a minimum theoretical price same rule. Even if the future prices of oil and of 4.6 cents per pound of ammonia; the The economic evaluation of alterna- gas remain uncertain, however, the rela- similar lithium nitride method would cost 4.3 cents per pound. Clearly neither could compete with the Haber process; moreover, these prices are based on ther modynamic requirements only and thus assume 100 percent efficiency,which could not be attained.

The development of a "supercatalyst" for ammonia synthesis, perhaps from the METABOLIC study of enzymes mediating biological PROCESSES fixation, might make it possible to com ATP (?) bine nitrogen and hydrogen at room tem perature. Although it may seem surpris

> ing, such a catalyst could have only a " a: marginal effecton the cost of ammonia. w z From the point of view of thermodynam w w ics a supercatalyst system would be only w a: u.. a variant on the Haber process, since the raw materials and the product would be the same and the change in free energy would be unaffected. Because virtually all the cost of Haber ammonia is the cost NITROGENASE, of hydrogen the price of the product ATP (?) would be little changed. I Among the oxidative processes low temperature ionization requires 3.3 kilo watt-hours of energy per pound of nitric I oxide produced. If this requirement were met with electrical energy (at former prices), the cost of fixation would be 2.6 cents per pound. Thermal activation re quires 18 kilowatt-hours per pound. Em the LFE nitrogenase back to the high.free.energy form. An equally plausible model (r ight) requires only one series of coupled reactions, the product of which is a high.free·energy suh. ploying electrical energy for that pur stance other than the nitrogenase, probably a hydrogen.active species (HAS). Nitrogen pose is hopelessly expensive: at least 14 combines with the HAS in a reaction catalyzed by the nitrogenase. The observed reo cents per pound of product. The direct quirement for adenosine triphosphate could be accounted for by either of the models. application of fossil fuels is considerably

© 1974 SCIENTIFIC AMERICAN, INC cheaper, but not cheap enough. The hour. At .05 cent per kilowatt-hour the dioactive, into the working medium, and theoretical minimum cost of 1.8 cents theoretical cost of producing nitric oxide these fragments would have to be re per pound already exceeds the cost of is about .17 cent per pound. At that price moved before the product could be mar Haber ammonia, and inefficiency has not chemonuclear fixation would definitely keted. Decontamination to acceptable been allowed for. In addition, because be competitive with the Haber process, levels might prove impossible, and even NHa is lighter than NO, .6 pound of am but in practice the price cannot be if it were found to be feasible, it would monia can be oxidized to yield one achieved. As we have seen, only about almost certainiy add to the cost. pound of nitric oxide, so that to be com half of the fission fragments give up their petitive the oxidative processes must energy by exciting or ionizing gas mole Future Fixation Methods manufacture nitric oxide not at one cent cules; moreover, only about half of the per pound but at .6 cent per pound. energy so transferred is available to pro If the problem of decontamination The most promising competitor of the mote fixation. (The rest is dissipated as could be overcome, and if a relatively Haber process is the chemonuclear ioni heat.) The overall efficiency is therefore modest improvement in efficiency could zation of air. As in low-temperature about 25 percent, and a more realistic be attained, chemonuclear fixation might electrical activation, 3.3 kilowatt-hours manufacturing cost for the product is .7 well become competitive with the Haber per pound of nitric oxide is required, but cent per pound. Since the product is ni process. Even considering the steadily the cost of raw fission energy is much tric oxide, the equivalent cost for am increasing cost of hydrogen, however, it lower than that of electricity. The ura monia is .6 cent per pound. does not appear that the chemonuclear nium-235 fuel employed in a nuclear re In addition to the problem of costs technique offers the prospect of a large actor costs about $20 per gram, but the there is a technological impediment to reduction in the price of fixednitrogen, energy released by fission is so great that the adoption of chemonuclear fixation. partly because the price of uranium 235 the cost of fission-fragment energy is The process depends on the release of is also expected to rise. The improve only from .05 to .1 cent per kilowatt- fission fragments, which are highly ra- ment, if any, would be modest, and al though it would certainly transform the nitrogen-fixation industry, it would prob ably have only minimal impact on agri cultural prices or practices. Extraordinary cost reductions are far more likely to result from the application of new techniques to more conventional processes, and in particular from poten tial methods of obtaining less expensive IONIZATION hydrogen for ammonia synthesis. Inex N, e N,+ + 2e + � pensive hydrogen is important in itself, since many industries other than nitro gen fixationrequire it; moreover, it has AF = +3 58 KCAl. recently been suggested that hydrogen gas could serve as a nonpolluting alterna tive to fossil fuels [see "The Hydrogen > Economy," by Derek P. Gregory; SCI Cl a: NO + 0 w ENTIFIC AMERICAN, January, 1973]. z w Besides fossil fuels the most obvious w w source of hydrogen is water, from which a: u. it can be extracted by electrolysis. The process is of course endoergic, theoreti cally requiring 57 kilocalories per mole, or 15.4 kilowatt-hours of energy per pound of hydrogen, and the economic N,+ e � N,' +e possibilities are not encouraging. The most advanced electrolytic cells now being developed promise an efficiency of 50 percent , so that about 31 kilowatt hours per pound would be required. At the energy cost prevailing before the price rises of the past year began, hy drogen manufactured by electrolysis would cost about 25 cents per pound. ACTIVATION OF AIR is the basis of several processes in which the free energy required Even if the cost of electricity could be for nitrogen fixation is supplied directly to nitrogen itself. Activation can be accomplished reduced to .2 cent per kilowatt-hour, by heating, by an electrical discharge or by ionizing radiation. In each case several oxides which is the transmission cost, electro of nitrogen are formed ; here only nitric oxide (NO) is considered. Excitation occurs when lytically made hydrogen would just a nitrogen molecule collides at sufficient energy with another molecule or with an electron maintain the former price of fossil-fuel or other particle. The excited molecule (N2*) can combine with oxygen to form ni tric oxide, or it may decay to the equilibrium state by emitting a photon. Collisions at higher hydrogen: about six cents per pound. Certain more innovative methods energy produce nitrogen ions (N2 +), which participate in a cascade of reactions with oxygen atoms and molecules. The result is the synthesis of two molecules of nitric oxide. might substantially reduce the cost of

© 1974 SCIENTIFIC AMERICAN, INC hydrogen-in theory even eliminate it en 100 tirely-by employing as a raw material , , the carbohydrates in waste organic ma , terials. In one such proposal the wastes , would be fermented by the action of ,, H2O microorganisms to yield methane, which , 80 could then be converted to hydrogen ,, and carbon dioxide by the conventional , re-forming and shifting methods. In an , other the Haber reaction would be by , �z passed entirely by employing a catalyst w , 0 , or a system of catalysts capable of com II: 60 w bining nitrogen directly with the hydro a.. w gen in carbohydrates. The latter process ...J 0 must remain speculative for the time � en being, since the necessary catalysts have I- 0 not been developed. ::::> 0 40 The raw materials for these processes 0 II: can be obtained virtually without cost. a.. Since the reactions involved are exoergic and energy costs are therefore also zero, either one suggests the prospect of free fixed nitrogen. Actually the cost would 20 r------i�------_+��------��------+_------__1 probably be high. Both processes would be slow, and enormous quantities of bulk solids would be required, only a C02 �: • C • small portion of which would be con ------" • ' • -. • ____ -. verted to useful products. If a catalyst O �� ------...J�------� -- ��------�----�� o 20 40 60 80 100 active directly on carbohydrates and RAW MATERIALS (PERCENT ORGANIC) molecular nitrogen could be developed, it might be best applied directly to the soil, where it could generate plant nu THERMONUCLEAR EXPLOSION could be employed to produce hydrogen for the Haber process from organic wastes. The products of such an explosion were calculated theoretical. trien ts in situ. ly, assuming a temperature of 2,000 degrees C. and a pressure of 500 atmospheres. A few In the fermentative processes, which hundred thousand tons of waste, in a water slurry, would be vaporized in an underground exist today and can be investigated, most cavity. Under optimum conditions virtually all the material would be converted to hydro. of the materiahs converted not to meth gen and carbon monoxide ; the carbon monoxide could be utilized to generate additional ane but to other products of little com hydrogen. Hydrogen manufactured in this way could cost as li ttle as one cent per pound. mercial value or else is left as unreacted residue. Furthermore, even if homoge neous organic wastes could be obtained as raw material, the biochemistry of fer produced for less than one-sixth cent per watt-hours per pound of hydrogen. That mentation is so complex that the outcome pound. is a large sum, but raw fission energy is of the reactions cannot be predicted or As in the chemonuclear process, the sufficiently inexpensive, so that the over controlled well enough to achieve com products of thermonuclear conversion all cost of the product might be competi mercially competitive efficiency. would be contaminated with radioactive tive with that of hydrogen derived from A chemically less complicated but substances; in this case, however, the fossil fuels. nevertheless more grandiose scheme has contaminants might be readily eliminat Because the heat of fission rather than been proposed by the author. A water ed. The most important one would be the the ionizing radiation would be utilized, slurry of organic wastes would be va hydrogen isotope tritium. It would be contamination of the product would not porized in an underground cavity by the reacted with nitrogen, by the Haber become a problem. Another technologi heat of a thermonuclear explosion. All process, to produce tritiated ammonia. cal difficulty has not been solved, how the substances would be dissociated into The ammonia would not be sold, how ever. Direct thermal dissociation re their component atoms, which would re ever, but oxidized to nitric oxide and quires a temperature of from 2,500 to combine, if the proper conditions were water; the tritium would be confined to 3,000 degrees C., which is far beyond established, to yield hydrogen and car the water (which could eventually be the range of practicality for industrial bon monoxide almost exclusively [see il sold as an isotope), and the nitric oxide, reactors available today; De Beni and lustration on this pagel. The process the primary product, would be free of Marchetti consider 750 degrees the would take advantage of the extremely contamination. maximum allowed. By substituting a se low cost of raw fusion energy, about .001 Another method for utilizing the heat ries of coupled reactions (involving iron cent per kilowatt-hour, or about a fiftieth of nuclear reactions has been suggested oxides and chlorides) for direct dissocia the cost of raw fission energy. By vapor by G. De Beni and C. Marchetti of Eu tion, they propose to reduce the temper izing a few hundred thousand tons of ratom. They propose to dissociate water ature required in the process to 1,000 de material at a time, hydrogen might be by direct thermal activation inside a nu grees, and it may be possible to reduce it manufactured for less than one cent per clear reactor. As in electrolysis, the mini further. pound, and ammonia could therefore be mum energy requirement is 15.4 kilo- A more distant possibility is the utili-

© 1974 SCIENTIFIC AMERICAN, INC zation of controlled nuclear fusion for sion. Finally, nitric oxide could be man than 60 years old but which remains the nitrogen fixation. Bernard J. Eastlund ufactured by thermal activation of air. most efficient of the methods available and William C. Gough of the Atomic As in any other method of thermal ac to us today. Energy Commission have pointed out tivation the efficiency would be quite A reduction by an order of magnitude that the exhaust gases of a fusion reactor low, and only about 2 percent of the in the price of fixed nitrogen would have would be so hot-at a temperature of mil reactants would combine to form nitric extraordinary worldwide consequence s lions of degrees C.-they could break oxide. Nevertheless, the cost of energy for agriculture. It is not our dependence down any material into its component would in this case be so low, about .001 on the Haber process itself that pre atoms and thus make pure elements cent per kilowatt-hour, that nitric oxide cludes such a price reduction but the de available for recycling. Such a "fusion could be produced for .018 cent per pendence of the Haber process on fossil torch" could be useful to nitrogen fixa pound. fuels for hydrogen. As the prices of pe tion in any number of ways, for exam The fusion torch is an attractive con troleum and natural gas continue to rise, ple by dissociating water or decom cept, and it would undoubtedly trans and as abundance becomes apparent posing carbohydrates. Organic wastes form many technologies in addition to shortage, this dependence could become could be heated and then quenched to nitrogen fixation; it appears that it will alarming. Consequently the most prom produce hydrogen and carbon monoxide not be available, however, for many ising fieldsof investigation for the im under controlled conditions by the same years to come. In the interim nitrogen mediate future are those that could lead mechanism operating without control in will almost certainly continue to be fixed to potential sources of less expensive an underground thermonuclear explo- by the Haber process, which is now more hydrogen.

ENERGY RAW ENERGY ENERGY TOTAL REQUIRED RAW MATERIAL REQUIRED COST COST (KILOWATT· PROCESS PRODUCT MATERIAL COST (KCAL. (CENTS PER (CENTS . HOURS (CENTS PER PER KILOWATT· PER PER POUND) MOLE) HOUR) POUND) POUND)

HABER NH3 H2 1 0 .0 4 - 1.04

CARBOHYDRATE·CATAL YST NH3 CARBOHYDRATES 0 0 - - 0

SUPERCATALYST NH3 H2 1 0 - - 1

METALLO·ORGANIC NH3 - - 179 5.7 .8 4.6

LITHIUM NITRIDE NH3 - - 165 5.3 .8 4.3

LOW·TEMPERATURE IONIZATION

ELECTRICAL NO AIR 0 180 3.3 .8 2.6

CHEMONUCLEAR NO AIR 0 180 3.3 .05 0. 17

THERMAL ACTIVATION

ELECTRICAL NO AIR 0 1,000 18 .8 14

FOSSIL FUEL NO AIR 0 1,000 18 .1 1.8

FUSION TORCH NO AIR 0 1,000 18 .001 0018

ECONOMICS OF NITROGEN FIXATION depends on the balance began to rise about a year ago. For the Haber process actual costs between the cost of raw materials and the cost of energy. Almost are given ; for all others the costs are theoretical minimums cal. the entire cost of ammonia made by the Haber process is the cost of culated from therm odynamic requirement!!. The biological process raw material (hydrogen); because the process is exoergic thermo· employing carbohydrates has a the oretical cost of zero but would dynamically no external source of energy is necessary. Methods that probably be too slow and have too low a yield to be prac ticaL eliminate the need for hydrogen require that energy be supplied. Chemonuclear activation of air has a low theoretical cost but be· Costs given are those that prevailed before the price of fossil fuels cause of its inefficiency would be only marginally competitive.

is limit of one such set per order. The To place your order, complete the form HE GOVERNMENT OF BELIZE (formerly a British Honduras) is proud to official issue price is $10 0. the set, and only below and mail it directly to the official Tannounce the first minting of its all those orders postmarked by October 31, minter of the coins: The Franklin Mint, new national coinage in 1974. To honor this 1974, will be accepted. Franklin Center, Pennsylvania 19091. occasion the Government has announ ced The circulating coinage of Belize will bear the issue of a Special Collector's Proof Set the same designs as the coins in the Col r------ORDER FORM------, -unlike any issued by any other country in lector's Proof Set, but will not be minted in THE NEW NATIONAL COINAGE the world today. silver. Six of the circulating coins will be OF BELIZE Every one of the eight coins in this special struck in cupro-nickel, one in ni ckel-brass, The Franklin Mint Franklin Center, Pennsylvania 19 091 Collector's Proof Set-from the ten-dollar and one in bronze. Proof and Specimen Please accept my order for the fo llowing : piece to the one-cent piece-will be minted Sets of the circulating coinage are also being D.One COLLECTOR'S PROOF SET, in solid sterlillg silver. made available to collectors. minted in solid sterling silver, at the . __ _ This set has been authorized by the Gov official issue price of $100. the set . $ TRADITIONAL PROOF SETS, con __TRA DITIONAL PROOF SET(S). ernment of Belize to provide collectors with taining flawless Proofs of the circulating QU'�"" mint ed in the same metals as the particularly beautiful and valuable examples circulating coinage, at the official coins are available at the official issue price issue price of per set ...... __ _ of the nation's new coinage. The face of each 535. ... $ of per set. The ordering deadline is __SPECI MEN SET(S). coin will bear an exquisitely sculptured $35. guu"f' October in the circulation metals, at the official portrait of one of the fascinating tropical 31. issue price of S20. per set ...... $ __ _ Total __ _ birds of Belize. The reverse will carry the SPECIMEN SETS, containing brilliant $ Add per set for postage and handling __ _ National Seal of the Government of Belize. non-proof specimens of the coins, may be $1. $ REMITTANCE ENCLOSED __ _ ordered at the official issue price of per S And every coin in this unique set will be a $20. M •. beautiful gem Proof-minted from special set. These sets will be available until autho Mrs. Miss---- ..,-; c.------dies so that the finely detailed design stands rized limits have been reached. -;;.;-;,,-,:;,,"',,;;;-.::;;, ,,'7'<;";c,:-; Address ______out in frosted relief against a brilliant, The total number of Col lector's Proof mirror-like background. Sets and Traditional Proof Sets to be issued City. State, Zip,______will exactly equal the number ordered by ORDERS FOR PROOF SETS All orders for Proof Sets October Thereafter, the special proof 31. MUST BE POSTMARKED BY OCTOBER 31.1974 must be postmarked by October 31, 1974. dies will be destroyed, so that no other Proof All orders subject to acceptance. Those who wish to acquire this historic Sets of the coinage of Belize can ever Please allow weeks for delivery. 1974 8 36-65 Collector's Proof Set are advised that there be minted again. �------�

Fron1 antiquity to modern times stairways have been built by rules of thumb. A study of how people move and expend energy in going up

and down stairs suggests a more rational approach to their design

by James Marston Fitch, John Templer and Paul Corcoran

ir Henry Wotton, a 17th-century Rutgers University. Our attention was tects must evolve a holistic theory of S English diplomat and writer, in attracted to the subject of stairs by cer human deployment in architectural k cluded architecture among his in tain general considerations of an archi space. Although much has been written terests, and he once offered certain stric tectural nature and also by reports of a about the dimensions of the body and tures on the construction of stairs. "To high accident rate on a monumental the expenditure of energy in various make,a compleate Staire-case," he wrote, stairway in New York: the four broad tasks, little of the material has any direct "is a curious peece of Architecture: The steps leading up from the plaza at Lin relevance to architectural problems. vulgar Cautions are these. coln Center to the walkway in front of Most studies of human movement, be "That it have a very liberall Light, the new Metropolitan Opera House. The ginning with the historic work of Ead against all Casualtie of Slippes, and general considerations had to do with weard Muybridge nearly a century ago, Falles. the deployment of people in space, par seem to have been largely descriptive. "That the space above the Head, bee ticularly in buildings. Moreover, they have usually focused on large and Airy ...because a man doth The way an individual acts in space is the motion of the individual subjects and spend much breath in mounting. the result of all the forces that play on neglected to provide much information "That the Halfe-paces bee well dis him at any given moment. The forces on the circumstances in which the tests tributed, at competent distances, for re are both external and internal, objective were made. Muybridge, for example, posing on the way. and subjective. The values of all of them photographed nude men and women "That to avoyd Encounters, and be are in constant flux. Much energy is re running up and down stairs but did not sides to gratifie the beholder, the whole quired merely to occupy space-to over provide data on the dimensions of the Staire-case have no nigard Latitude, that come such forces as friction, gravity steps or show how motion would have is, for the principall Ascent, at least ten and atmospheric pressure-let alone to been modified by stairs of other propor foot in Royall Buildings. accomplish socially productive work. tions. Similarly, members of the remark ' "That the breadth of every single Step Hence the conservation of energy is a able Ducroquet family of French ortho or Staire bee never lesse then one foote, matter of considerable consequence to pedic physicians have carried on for nor more then eighteen inches. the individual. decades a study of normal and patholog "That they exceede by no meanes People conserve energy by a complex ical walking. All oLit, however, was on halfe a foot in their height or thicknesse; feedback system in which sensory input level places. How would it be altered for our Legges doe labour more in Ele continuously modifies spatial orienta by stairways? vation, then in Distention.... " tion. Information the senses provide on The simple good sense underlying environmental events is converted into he need for holistic data is nowhere Wotton's "vulgar Cautions" is quite often decisions on the movements to be made. Tmore apparent than in the design of neglected or forgotten in buildings to This marvelously sensitive and precise stairs. Here is a device almost as old as day. The pedestrian encounters stairs cost accounting of the input and output architecture itself (the ramp may be old that are distinctly uncomfortable if not of energy is largely carried on uncon er), and yet little has been written on dangerous-not because they are inade sciously, or at least below the level of the subject. When one examines the ma quately maintained or badly eroded but consciousness. It is therefore difficult to terial, as we have had occasion to do, it because the geometry of their design observe and quantify. turns out to consist largely of empirical does not match the natural human gait. Nonetheless, if the overall effective rules of thumb. No one seems to have On such a stairway one risks an accident, ness of architecture is to be raised above examined closely the sense of comfort or either from not b�ing aware of irregular its present unsatisfactory level, archi- strain, safety or danger that the user ex- ity or from not paying attention to it. The authors of this article have been looking into the design of stairs over a period of years. In that time important WOMAN ON STEPS appears in the photographs ,on the opposite page, which were made contributions to the work have been with a stroboscopic flash lamp as she went up and down a short flightin a laboratory. It was made by Jose R. Bernardo, an architect one of four flights of differing design built to test how the various designs affected the hu· in New York, and Neville O'Reilly of man gait. The woman wears a red stocking and a white one to assist the observations.

© 1974 SCIENTIFIC AMERICAN, INC periences in climbing or desccnding a The physiological factor is more or becn cstahlished by hcavy hoopskirts. particular kind of stairway. less constant. The metabolic rate of a All stairs impose a certain gait and The restraints on all human move man climbing a "normal" set of stairs at hence a deRnite psychic orientation on ment, including travel on stairs, are both a normal speed is two to Rve times that the user. This constraint has always been physiological and cultural. The physio of a man walking on a horizontal surface well understood bv thc architects of logical restraint is a function of the Cll at three miles per hour. The cultural fac monumental structures such as temples, ergy required to lift or lower the body tor is variable. Naked young men led the palaces and opera housf's. In those places from one point in space to another. The Panathenaic procession up the ramp of the stairway plays an important role in cultural restraint is a function of the the Acropolis, whereas the pace and pos the required ceremonial behavior of both gait and posture dictated by the cus ture of Empress Eug&nie on the stairs at climbers and beholders. No comparable toms and costumes of the culturc. the palace of Versailles would have attention, however, has been paid to the

LINCOLN CENTER STAIRWAY in New York is of unusual ron in front of the Metropolitan Opera House to a busy plaza, so that (iguration, having exceptionally shallow risers and deep treads. In people approaching it from the direction of the opera house may addition it -leads in the downward direct jon from a broad walkway not see it. The stairway has been the s('ene of nl1lllerOLl� st.umble:::.

© 1974 SCIENTIFIC AMERICAN, INC design of stairways for mundane utili tarian purposes. The stairway at Lincoln Center ap pears to impose an awkward gait on its users because of its shallow risers (3.375 inches) and deep treads (25 inches). As originally installed the steps were hard to see because they were made of a light travertine similar in color to the rest of the plaza. Moreover, they are a consid erable distance away from the front of the opera house, and a pedestrian ap proaching the busy plaza from the direc tion of the opera house may simply not notice them-a surmise reinforced by the fact that most of the people who fell or stumbled were descending the steps. The full extent of the trouble with the stairway is not known, since both the architects and the management of the center have declined to discuss the mat ter. It is known, however, that the acci dents have been frequent enough and se rious enough to have led to a number of lawsuits and to a series of physical modi fications of the stairway. Indeed, at the places where pedestrian trafficis the heaviest the steps have been replaced with ramps. In much of the remaining space the steps have been closed off with bronze railings. Since the general configuration of the steps satisfies the conventional standard for the design of exterior stairs, we were intrigued by the evidence that something was wrong with them. We were also mo tivated by the scantiness of the archi tectural literature on stairways. We de cided to inquire into the matter in the hope of providing a better basis for a theory of design of stairs.

he technical literature on stairway ac- Tcidents proved to be somewhat lim HELICAL STAIRS are in City Hall in New York. They carry traffic between the entrance ited in that the few reported studies had hall and the rotunda. A study of how people traveled up and down the stairs showed that in focused on accidents in the home. Resi ascent 65 percent of the users kept to tbe right on the flight at the right, whereas no one dential stairways are usually steeper kept to the right on the other flight. In descent the patterns of use were essentially reversed. than those in public places and more deliberately utilitarian. Nonetheless, the studies indicate that most stairway acci the tread can be satisfactorily combined. creased by a regular and fixed amount dents involving injuries severe enough We therefore undertook a series of to allow the foot to be raised in climbing to require medical attention occur dur investigations directed at identifying stairs. Blondel derived a formula stating ing descent and that in a high percentage riser and tread sizes and combinations that the pace must be decreased by two of the cases the stairways lack handrails. that seemed to be most congruent with inches for every inch of riser. Expressed Slipping is the primary cause of stairway the human gait and hence felt safe and mathematically, the formula specified accidents. comfortable to users. We were by no that the depth of the tread should be 24 The steepness of a staircase appears to means the first in the field. Almost every inches minus two times the height of the be unrelated to the accident rate. Di architectural writer since Vitruvius has riser, or that the total of the tread and mensional irregularities, caused by poor expressed views on suitable combina two times the height of the riser should design rather than wear, are strongly tions. It was not until about 1672, how be 24 inches. correlated with the accident rate. None ever, that Fran<;ois Blondel, director of The apparent anthropometric logic of the studies examined a subject of par the Royal Academy of Architecture in behind Blondel's thesis recommended his ticular interest to us: the size of risers Paris, concluded from personal observa formula to generations of architects in and treads and the various ways in which tion that the normal pace in level walk spite of the fact that, in stairways where the height of the riser and the depth of ing (24 inches, he said) must be de- the risers are to be made higher or lower

© 1974 SCIENTIFIC AMERICAN, INC than usual, the rule produces either ex tremely narrow or extremely wide treads . Moreover, the average human being is bigger now than most people were in the 17th century, and today's inch is shorter ' than the one employed by Blondel in his calculations. It is therefore somewhat surprising to find BlondeI's rule or varia tions of it still entrenched in many build ing and fire codes. The National Fire Code, for example, specifies that the depth of the tread plus two times the height of the riser should total between 24 and 25 inches. Our study also led us to a number of apparently quite arbitrary formulas that govern only utilitarian interior stairs; exterior stairs are either not mentioned or are explicitly exempted. The formulas are notable for their lack of unanimity. For a four-inch riser, as a case in point, treads ranging in depth from 13 to 28.3 inches are acceptable. The formulas are particularly equivo cal when the angle of ascent is less than 20 degrees. Here the architect is expect ed to design stailways for which the formulas offer no consensus. Faced with such a situation he is apt to fall back on intuition, which may be what happened in the design of the unfortunate stairway at Lincoln Center.

o test the effect of various stairways Ton the user's gait and sense of com fort we built replicas of four stairways and photographed people walking up and down them. Although each one was only three feet wide, it reproduced ac curately the configurationof the real steps: the ones at Lincoln Center, a monumental Hight in the central plaza at Columbia University and two ordinary stairways meeting the standards of the New York City building code. Each replica consisted of four steps so as to make it comparable with the Lincoln ' Center stairway. The angle of ascent ranged from 7. 7 degrees (Lincoln Cen ter) to 36.8 degrees (city code). Men and women wearing ordinary street clothes and their own choice of shoes were photographed in the light of a high-speed repetitive flash lamp as they went up and down the steps. These exploratory tests confirmed our suspicion that certain step configura tions, such as the ones in the Lincoln Center stairway, impose a curiously ir regular gait on both men and women in both ascent and descent. We decided

RISER AND TREAD COMBINATIONS are portrayed according to a formula derived that our next move should be to exam some 300 years ago by Fran�ois Blondel, director of the Royal Academy of Architecture in ine the relation between gait and the Paris. He held that the depth of the tread should be 24 inches minus two times the height of configuration of steps in a methodical riser. Application of formula is shown here for risers of five (top), seven and nine inches. way, testing the entire range of riser-

© 1974 SCIENTIFIC AMERICAN, INC REPLICA DESIGNS embodied 8 variety of riser and tread con (b) had five-inch risers, 17-inch treads and a pitch of 16.4 degrees_ figurations and pitches_ The Lincoln Center configuration(a) had The other designs are found in many public places. One (c) had 3.37S-inch risers, 2S-inch treads and a pitch of 7.7 degrees. A replica six-inch risers, 12-inch treads and a pitch of 26.6 degrees. The other of a monumental stairway on the campus of Columbia University (d) had 7.S-inch risers, lO-inch treads and a 36.S-degree pitch. tread combinations normally found or a rhythm bordering on a run; the second for every configuration of steps. It bears recommended. For this purpose we em was the normal pace that people have out what we found in the accident stud ployed a mechanical stairway that op been observed to use on stairs , and the ies, which was that many of the falls erated as a treadmill. third was a speed close to slow motion. occurred when people were hurrying The stairway had been developed On the basis of 1,291 successful tests down the stairs. originally by the U.S. Department of we developed equations that enable us It appears from our results that the Agriculture for monitoring the energy to predict with confidence the number safest stairs for descent are not the same expenditure of women on stairways. It of missteps that can be anticipated with as the ones for ascent. In descent treads can be adjusted for a range of pitch from any of the riser-tread combinations. (A that are at least 12.3 inches deep will 22 to 45 degrees, riser height from four misstep would not necessarily lead to a result in the fewest missteps at all to 11 inches, tread depth from seven to stum ble or a fall. As defined for the tests, speeds. The number increases with each 15 inches and speed of ambulation from a misstep is a step that is not complet reduction in tread size. Treads less than about 20 feet of vertical rise per minute ed within certain predetermined toler nine inches deep will be associated with to about 100 feet. Our tests were carried ances.) the greatest number of missteps regard out at the metabolic research laborato The results show that fewer missteps less of the height of the riser and the ries of the Helen Hayes Hospital, a New are likely in ascent than in descent at all speed of ambulation. Risers in the range York State physical rehabilitation facil speeds and for all riser-tread combina from 4.6 to 7.2 inches are, however, like ity. Sixteen subjects participated. They tions. Indeed, all the test stairs can be ly to cause fewer missteps in descent wore special rubber overshoes fitted with climbed with little likelihood of a mis than lower or higher ones. Our findings pressure-sensitive switches connected to hap, at least at one of the three speeds. suggest that in the rare situations where a polygraph. In each trial the polygraph Nonetheless, the results indicate that a a stairway is to be designed for unidirec recorded the duration of the contact of range of riser-tread combinations, hav tional movement the configurationmight the subject's toes and heels with the ing risers of from 6.3 to 8.9 inches and differ according to whether the move treads and also the rhythm of his gait. treads of from 7.7 to 14.2 inches, results ment is to be up or down. The tests were run at three angles of in stairs that are likely to be safer to pitch (25, 35 and 45 degrees), with three climb, as reflected by the low number of study made by Joan S. Ward and different riser-tread combinations for missteps, than other configurationsof the A William Beadling of the Loughbor each angle. We therefore had nine con test group. ough University of Technology in En figurations, each of which was tested at In descent the fewest misstep�. were gland suggests why smaller treads raise three different speeds of ambulation. recorded when the subjects were walk difficulties in descent. Ward and Bead The first speed forced the subject into ing at the slowest pace. This finding held ling noted that, as the size of the tread

87 © 1974 SCIENTIFIC AMERICAN, INC is progressively decreased, a point is deep, allowing for a nominal quarter minimum allowed by most codes now is reached where the shod foot can no inch between the heel and the riser and 9'� or 10 inches. longer fit on the step without being for the toe of the shoe to overhang the Having identified certain riser-tread twisted sideways . This awkward move step by about 1% inches. A more con combinations that are least likely to ment induces a crablike gait and a poor servative design, which would accom cause falls, we turned to the question of ly balanced posture. modate 95 percent of the population, what combinations might be more com The crablike gait will begin to ap would make the smallest allowable tread fortable than others in terms of the en pear whenever the tread is too small for 11.1 inches. ergy demand they impose on the user. the foot. Therefore if stairs -are to be These data suggest that 11-inch treads Put another way, the question we sought adequate for the largest people, the should be a reasonable minimum, at to answer was: Are some stairs more tread will need to be at least 11.8 inches least for stairs in public places. The tiring than others? Again we found the published mate rial scanty. A good deal has been writ ten about the energy cost of level walk ing and walking on ramps, but the tech nical difficulty of measuring the meta bolic cost of going up or down stairs has limited the number and quality of the studies published on that subject. The problem is to separate with precision the energy expended on the basic functions of life from the additional energy spent climbing stairs. The separation is par ticularly difficult when the stairway is typical of the ones generally encoun tered. To simplify the technical procedures for measuring energy expenditure on stairs one needs a long flight of stairs, which is relatively uncommon. One team of investigators carried out its tests on a flight of stairs that went up a mountain. Other investigators chose to have their subjects work on shorter flights but make several ascents and descents on each of the tests. This procedure effectively prevented the investigators from sepa rating the work of descent from the work of ascent. Once again the mechanical stairway came to our rescue, since it enabled us to simulate stairways of any length. To carry out the metabolic studies we em ployed 19 differentriser-tread combina tions and three different rates of vertical ascent. We measured a subject's energy expenditure by recording the amount of oxygen he consumed while walking on the treadmill and subtracting from that total the energy cost of the basic meta bolic functions. With 639 observations we formulated an equation that enables us to predict the energy demand of any of the stair combinations in terms of the speed of ascent, the pitch of the stair way, the height of the riser, the depth of the tread and the weight of the subject.

The experiments showed that walking on stairs produqes a pattern of energy expenditure that differs notably from the MECHANICAL STAIRWAY enabled the experimenters to test a number of different riser and tread combinations, pitches and speeds of ambulation for both their effect on the human patterns exhibited in walking on the lev gait and the amount of energy required to climb under various conditions. Here the ma el or on ramps. In level walking and on chine appears in a double exposure that p�rtrays how it can be set at different angles of ramps people generally choose a speed of pitch and how it serves for both ascent and descent. The apparatus is at the Helen Hayes ambulation at which the total energy Hospital in West Haverstraw, N.Y., a state facility where the experimental work was done. cost of walking a given distance will be

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PROPORTIONING OF STAIRS to conform with the natural, in. depth of tread (color) and angle of steepness for five designs. These formal human gait is depicted. The chart shows riser height (gray), designs and several others were found suitahle by the authors. at a minimum. The total energy cost of ment. When one must consider the en stairs with high risers and small treads, walking a mile on the leve! is much high ergy cost of both horizontal and vertical however, demand no more effortthan er at one mile per hour or six miles per movement, one finds that a ramp with a shallower stairs with much lower risers hour than it is at three miles per hour. gradient of less than about eight degrees and large treads. The findingshave im People therefore usually choose speeds is more economical than any stairway plications for the design of stairways. close to three miles per hour for walking. that is likely to be epcountered in normal Clearly the findings support the gen A similar phenomenon of optimal speed activity. eral validity of Blondel's 300-year-old is also exhibited by people on ramps. On the basis of these considerations thesis. For comfort, in terms of low rates This finding does not hold good for one can conclude that in a conventional of energy expenditure, a stairway should walking on stairs. People seldom climb two-story house a stairway is more eco be designed to provide a congruence stairs at a speed that is most economical nomical than a ramp in terms of the between its riser-tread combination and in tenns of total energy expenditure. Ap total energy expenditure. (The stairway, the human gait. To keep the rate of en parently stairs are barriers to which the of course, is also more economical in ergy expenditure low, the designer must human being is not well adapted physi terms of the amount of space it takes up.) either combine low risers with deep cally. Climbing stairs is perhaps more In a transit terminal, however, where treads or reduce the size of the treads as like running, which obviously does not one often needs to travel considerable the height of the risers increases. It must conserve energy. distances horizontally as well as ver be said, however, that the formulas of One can consider ramps and steps tically, a ramp within the normal range Blonde! and his successors are too re simply as prosthetic devices for assisting is more economical than any stairway strictive, too narrowly idealistic and too the human organism in climbing from in terms of the total energy demand. unresponsive to hllman adaptability. Hoar to floor and can compare them It is not the total energy cost of an The range of options for combining risers invarious geometric combinations in action that one perceives as fatigue. Fa and treads at any level of energy ex tenns of the energy expended in using tigue is experienced after expending en penditure cannot be expressed satisfac them. Ba�ing our observations on the ergy at a high rate over a short period torily by a linear equation. usual rate of climb, we found that within of time. Clearly it takes about the same Let us now assemble the conclusions the range of the observations the total amount of energy to run up a stairway as from the analysis of gait and the analysiS energy cost declined as the stairway be to walk up, but running is more tiring. It of energy expenditure and apply them to came steeper. On ramps also the total is therefore worth considering the rates the design of stairways. Assuming that energy cost per vertical meter decrease� of energy expenditure imposed by vari the stairway is to have people going both as the pitch is increased until a pitch of ous riser-tread combinations, particular up and down, the designer can choose about 17 degrees is reached; from there ly since the studies of step geometry by frolll a broad range of riser-tread combi on the energy cost rises. Ramps, how Ward and Beadling indicated that the nations. The stairs will have risers of ever, demand a higher expenditure of stairways least preferred by a group of from four to seven inches coupled with energy per meter of rise than the usual test subjects were the ones demanding treads of from 11 to 14 inches. A stair range of stairs. high rates of energy expenditure. way designed within this range will re Our findings have implications for de We found that the rate of energy ex sult in fairly low rates of energy expendi sign in structures where the sale concern penditure on stairs is generally greater ture (at normal speeds) and a low rate of isthe total energy cost of vertical move- for high risers than for low ones. Steep missteps.

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MOUTH MARKINGS of host nestlings, which stimulate the host ling, the paradise widow bird (b), of a second host species, the pur parents' feeding response, are mimicked in detail by all the para ple grenadier (c), and its parasite, the straw-tailed widow bird «(/), sitic species of African widow birds_ Shown here are the markings and of a third host-parasite pair, Jameson's fire finch(e) and the of a host-species nestling, the melba find,\fI), and its parasitic sib- purple combassou (f 1_ Many other mimicries of the type are known.

Various specie� of birds lay their eggs In the nest of another bird, which then incubates the eggs and feeds the young. The wido"r birds of Africa achieve this result by some remarkable feats of nliinicry

by Jurgen Nicolai

he number of eggs a female ani Birds that practice this kind of para formidable hooks at the tip of its beak; Tmal produces is inversely propor sitic parenthood are found around the its host's offspringare all soon fatally tional to the probability that the world. Among them are various mem wounded, leaving the parasite to con egg will give rise to a female that pro bers of the cosmopolitan family of cuck sume all the food the host provides. duces more eggs. All invertebrate ani oos, some species of American cowbirds, Some cuckoo nestlings simply nudge mals and most lower vertebrates need to a black-headed duck (Heteronetta atri their foster siblings out of the nest dur broadcast eggs by the hundreds and capilla) in South America, all species of ing the first few days of life; others ma thousands in order to ensure the exis honey guides and certain weaverbirds in ture so much more rapidly than their tence of subsequent generations. The Africa. I have investigated the behavior nestmates that the foster siblings' devel number of eggs laid by a bird, although of this last group, observing in particular opment is inhibited and they die pre much smaller, also reflects the probabil the several species of a subfamily, the maturely. ity of reproductive success. Consider the Viduinae, within the family of weaver In the long run, of course, strategies greatest of ocean birds, the wandering birds. The birds in this subfamily are that result in the death of the host's albatross. It occupies breeding grounds commonly called widow birds. My work young are unproductive. The parasitic on isolated islands of the Southern Hem has been conducted both in the field parent needs to use the nests of several isphere where it is completely undis and in our laboratory at the Max Planck host pairs each year and a dwindling turbed, and the female albatross lays a Institute for Behavioral Physiology in host population means fewer nests. The single egg every other year. In contrast, Seewiesen. widow birds have evolved a strategy that most species of European tits and both circumvents this problem; like the egg species of goldcrests respond to the �though a parasitic bird has overcome strategy, it is imitative. Each widow stresses of severe winters and numerous the disadvantage of putting all its bird nestling is indistinguishable from predators by laying two yearly clutches eggs in one nest, the very nature of its its host's nestlings in size, in color and of eggs, each numbering between eight solution to the problem introduces cer markings, in gesture and in call. Thus and 12. tain other difficulties. For one thing, if the intruders can grow up among their Any bird that is subject to severe en parasitic parenthood is to be successful, alien nestmates with no risk of being re vironmental stress or predation pressure the parasite's reproductive cycle must be jected by their foster parents. Such a is at a reproductive disadvantage. It synchronized with the cycle of the host strategy ensures that the numbers of the must incubate its eggs with the heat of species. For another, it would be fatal host population do not diminish. its own body, and so the eggs must be if the host rejected either the parasite's It seems surprising that the widow kept all in one place, usually in a nest. A egg or the hatchling that emerged from birds should have evolved this particular predator therefore needs to search out it. With respect to the egg a strategy of strategy. Their chosen hosb-various only a single target. One group of birds, mimicry has evolved. For example, par species of finches, the entire family Es the turkeylike mega pods of Australasia asitic cuckoos lay eggs with markings trildidae-are noted for having mouths and the Pacific, has surmounted this that closely resemble those of the host's that are colored and marked in a com handicap by an ingenious stratagem. In eggs. Widow-bird eggs are unmarked, plex and conspicuous manner [see illus stead of building nests they pile up as are their host's; they differfrom the tratiol1 all opposite page]. No two of the mounds of plant material where they eggs of the host species only slightly in 125 species of estrildid finches have bury their eggs to be incubated by the size and shape. identical mouth markings. The color of warmth of plant decay [see "Incubator \Vith respect to the acceptance of the the palate may be whitish, red, yellow Birds," by H. J. Frith; SCIEKTIFlC AMEH hatchling the parasite strategies that or bluish. The palate markings may lCAN, August, 1959]. Still other bird spe have evolved are various. Several spe form a three-spot pattern or a five-spot cies have discovered another solution to cies of cowbirds punch tiny holes in the pattern or may be only a fine horseshoe the problem. They deposit their eggs, host's eggs before depositing their own, shaped line; the spots themselves may be one at a time, in the nest of another spe thus ensuring that no host egg ever black or violet. Moreover, the fledglings' cies; the eggs are then incubated and the hatches. An African honey-guide hatch gape papillae vary in shape and color. hatchlings raised by the host. ling emerges from its egg armed with Thev may be ivory white, cornflower

© 1974 SCIENTIFIC AMERICAN, INC blue, yellow or faintly violet, and they may appear as simple thickenings or re semble small pearl-shaped warts. In parallel with these elaborate mouth markings there has evolved among the estrildid finches a precise, genetically based "knowledge" of species-specific patterns and stimulus-receiving mecha nisms that are correspondingly selective. By the simple experimental method of placing nestlings of one finch species in the nest of other species my colleagues and I have demonstrated that t he par ent birds will feed only the nestlings that display the appropriate species-specific markings. Even minor deviations in pat tern are noted by the parent birds, and the deviants are ruthlessly weeded out by starvation. A parasite nestling constantly inter acts with its foster parents from the time of its emergence until it leaves the nest. The host birds are thus an essential part of the parasite's environment. The host sets a series of examples that instructs the paraSite with respect to such matters as environmental standards and feeding habits. One instance of this process of parallel adaptation is the synchroniza tion of the parasite's and the host's re productive cycle.

NIost species of estrildid finches breed during the rainy season. The finches' gonads begin to swell when, after months of drought, a series of showers brings the vegetation to re newed life. The timing is appropriate because the increase in the food supply that comes with the rainy season makes it easier to feed nestlings. Several finch species begin their breeding activities when the rains start; others do not be gin until the middle of the rainy season or toward the end of it. A few species, such as the yellow-winged pytilia and the aurora finch of West Africa, delay their breeding until the dry season, a time when they find feeding conditions appropriate. In each of these instances the para sitic widow birds synchronize their re productive cycle with that of their host. One element in the cycle is that when courtship begins, the male widow bird displays a splendid and conspicuous plumage. The molt into breeding plu mage occupies a period of four to six weeks. This means that the maturation of the widow bird's gonads, which initi ates the molt, actually occurs sometime before the host's gonads mature. To cite some examples, the paradise PARASITIC ADULTS, the female (a) and male (b) paradise widow hird, do not in any widow bird and the straw-tailed widow way mimic the appearance of the foster parents of their young, the female (e) and male bird have hosts that breed during the (d) melba finch. The male paradise widow bird is seen in its bright breeding plumage. rainy season. That requires the male

© 1974 SCIENTIFIC AMERICAN, INC widow birds to develop their breeding plumage before the end of the dry sea son. Similarly, two species of widow bird, the Togo paradise widow bird and the Kongo paradise widow bird, have hosts that breed during the dry season. The male parasites' molt must therefore take place toward the end of the rainy season. Under these circumstances it is clear that the onset of the parasites' re productive activity cannot simply be triggered by the onset of the hosts'; it is evidently set in motion by some kind of seasonal rhythm. The specific rhythms remain unidentified but one is justified in assuming that, because the rainy and dry seasons follow each other with great regularity in most of Africa, the gonads of rainy-season breeders begin to be stimulated after the passage of a certain length of dry-season time, and vice versa. Now, in any fine-tuned system of par asitic adaptation one of the greatest potentials for disruption is accidental YOUNG PARASITES, unlike adult parasites, closely resemble their host siblings in ap hybridization between species of para pearance. Profiles at left show a paradise widow·bird nestling (a) and a melba·finch nestling sites that are closely related and coexist (b) 13 days after hatching; profiles at right show a straw-tailed widow-bird nestling (c) and in the same area. As far as the widow a purple-grenadier nestling (d) 15 days old. The young are independent after five weeks. birds are concerned, any hybrid off spring would display intermediate mouth markings rather than markings species to another, and each species-spe Let us examine in detail the song of that match those of their foster siblings. cific repertory perfectly imitates the mo one widow-bird species. The straw That in turn means they would be re tifs characteristic of the widow bird's tailed widow bird of East Africa (Tet fused food by the host species of both finch host. We therefore call such motifs raenura fischeri)ranges over the scrub parents. This hazard, with its long-term host phrases. They include the finch's savanna of that region from southern potential for the extinction of all widow long-distance call, its contact call, its dis Tanzania northward into Ethiopia and birds, has been avoided by the evolution tress and anger calls, its greeting phrases Somalia. The male's breeding plumage is of a kind of behavior that is unknown and, of course, its routine song. The par black and yellow and its four conspicu among other parasitic birds. In brief, asite's mimicry of this repertOlY is so ously elongated central tail feathers look when the male widow bird sings, it in exact that it sounds like the finch'sto like yellowish blades of dry grass. Dur cludes in its song certain unique finch the human ear and looks like it in a ing the breeding season the male perches species phrases it has learned from its spectrogram [see illustration on page high in small trees or thornbushes and foster parents. 97]. Furthermore , the host finch itself twitters its song unceasingly from early Widow birds are polygamous. At the cannot distinguish between the widow morning until sunset. The first motif in start of the breeding season a male bird's imitation and the song of its own its repertory is usually the contact call of stakes out a large territory that it de species. its finch host, the purple grenadier, fends against potential rivals. Through out the breeding season the male perches on certain selected trees and bushes in the territory and sings its unique melody. If one compares the songs of various widow-bird species, either by listening or by analyzing sound spectrograms, it soon becomes apparent that the songs of all species have a few phrases in common. For example, they all include harsh chat tering sounds; the motif is evidently re lated to the vocalizations produced by the widow birds' closest relatives, the bishop birds of the subfamily Euplec a c d tinae. Since these chatterings appear to

represent an ancient genetic heritage, we MIMICRY IN THE NEST extends to the size and shape of the egg laid by the parasite. At call them widow-bird phrases. left is the egg of the melba finch(a) and of the paradise widow bird (b); the parasite's egg The major portion of any male widow is only slightly larger and more rounded than the host's. At right is the egg of another host, bird's song consists of quite different the red·billed fire finch(c), and the egg of its parasite, the black·winged combassou (d). As vocalizations. Its motifs vary from one centimeter grid shows, the host and parasite eggs are virtually identical in size and shape.

© 1974 SCIENTIFIC AMERICAN, INC Uraeginthus ianthinogaster; this is a long trill. The mimicked phrase is repeated several times, increasing and decreasing in loudness. It is followed by other ele ments of the host's repertory. They in clude the brief "call" phrase used by the male to attract the female, the male's clacking song, a chase call, whispering nest calls and the shrill begging calls that fledglings use; in all, the mimic's reper tory includes a total of eight finch motifs. Each mimicked vocalization is separated from the next by an interval, and each lasts the same length of time as the host's. The finch potpourri is interspersed with three differentwidow-bird phrases that, like the mimicked host melodies, occur in unpredictable sequences. The eight finch motifs give the male straw-tailed widow bird effectivecommand of the entire vocabulary of the purple grena b dier. The same pattern of host-melody mimicry is apparent in almost all other species of widow birds. The shaft-tailed widow bird of South Africa (Tetraenura regia) mimics the repertory of its host , the violet-eared waxbill (Uraeginthus granatinus). Each of the five species of the paradise widow-bird genus (Stega· nura) copies the host melody of the par ticular species of the finch genus (Py filialit parasitizes. The same is true of the seven species in the genus of short tailed black combassous (Hypochera) that mimic all seven species of the genus of fire finches (Lagonosticta). Indeed, in only two instances has it been impossible to demonstrate the presence of host phrases in a widow bird's song; these cases are the two species of the genus Vidua, the blue widow bird of East Africa and the pin-tailed widow bird, which is found in the sub-Saharan re gions of the continent. By determining which are the host phrases in a male widow bird's song, it is even possible to predict the identity of the host when it is not known . Such predictions have been made more than once in our laboratory after careful anal ysis of the songs of captive widow-bird males, and I was later able to prove their accuracy. In the field in East Mrica we found the appropriate young parasites among the nestlings of exactly those spe cies of estrildid finches that had been identified as probable hosts.

he use of host melodies in widow- Tbird singing serves a vital purpose: it BREEDING PLUMAGE of parasitic widow birds develops during a four·to·six·week pe· is a barrier to hybridization. How this riod. Seen here are a male straw·tailed widow bird (a) and its bost, a purple grenadier (b), isolating mechanism is acquired is best and below them a male purple combassou (e) and its bost, a Jameson's fire finch(d). The shown by a review of the widow-bird parasite's breeding cycle must syncbronize witb its host's to ensure synchronous egg.laying; life cycle. The young nestlings ' first in order to grow breeding plumage, however, a parasite must enter its breeding cycle first. weeks of life, as they share the nest of

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SONG MIMICRY, a meticulous imitation of the host male's call, mimicry of this part of the finch's song by a male paradise widow learned by the parasite male while a juvenile, is demonstrated by bird. The third sonogram shows a two·second segment of the song these paired sonograms. The top sonogram shows the final seconds of the violet-eared waxbill; the fourth is mimicry of this segment of a Damara melba finch's song; the sonogram directly below it is of the song by the waxbill's parasite, the shaft·tailed widow bird.

© 1974 SCIENTIFIC AMERICAN, INC their host siblings. are ones of constant for example "I grew up among the contact with their foster parents. The same host species that you did!" In my WINETALK parasites become indcpendent at the age view the signal contains a message with of five weeks, but eyen after that they a much deeper biological meaning; it by Austin. Nichols continue to live for some time among might be paraphrased as "I have inher their host siblings. It is only later that ited the same adaptive characteristics Chateau Figeac takes its name from they form a flock with other juvenilcs of that you have and so our offspring will St-Emilion but its breed is Pomerol. their own species. have the same chances of survival." Breed. The unique taste charac During these weeks of dependence teristics that mark a great wine. and association the young widow birds r is clear that the adult widow birds' are imprinted to the host species; this general adaptation to their hosts' song For Chateau Figeac, it means a imprinting is a decisive factor in their repertory, breeding rhythms and feed claret that's closer to Pomerol than later reproductive behavior. When, at ing habits, along with their nestlings' St-Emilion. the age of seven to eight weeks, the perfect mimicry of foster-sibling mark Located on a gravelly strip of widow-bird juveniles first engage in pre ings, movements and calls, can only land that extends into Pomerol. its mature sexual behavior as all songbirds have been the result of an extended evo excellent drainage and mineral con do, there arises in the parasites a quite lutionary process. As we have come to tent give Figeac a tremendous narrow and specific interest in the activi know the identity of more and more ties of the host species. Whereas other host species of estrildid finches some of balance and breed. The Figeac vine songbirds not only play at building nests the mechanisms of the process respon yard-with its large proportion of during this phase but also feed and court sible for these unusual adaptations have Cabernet-Sauvignon grapes -pro one another, the attention of the juvenile become apparent. It seems that in effect duces a dark, ruby-black claret that widow bird is concentrated on two as the potential for the evolution of a new is unique to St-Emilion. pects of its hosts ' adult behavior. The species of widow bird has arisen in the Recognizing and assessing the focus of interest depends on the sex of past only when a new species of host breed of a wine takes the ability of the widow bird. finch has evolved. As the female widow bird approaches an expert. Perhaps a more conven Consider the relations between hosts sexual maturity her interest is concen and parasites from a taxonomic view ient way is to recognize the mark of trated on the hosts' reproductive cycle. point. Two species of the widow-bird Austin, Nichols. The parasite checks frequently on the genus Tetraenura are known: the straw progress of the host pair's nest-building. tailed widow birds and the shaft-tailed. The female also synchronizes her own The estrildid finches parasitized by ovulation with that of the host female; these two related widow-bird species are this ensures that her own egg is ready at also two species of the same genus, about the time the host female produces Uraeginthus. In turn five species of par her second or third egg. As a conse adise widow birds are the parasites of quence the young parasite will hatch five species of another finch genus, and at about the same time that its host sib the seven species of combassous are lings do and will be their equal in the linked to seven species of fire finch. Even competition for food. though the specific hosts of the two The male widow bird's concentration widow birds of the genus Vidua remain is differentlyoriented. During the most unknown, we are certain that they are impressionable phase of its youth its in one or another of the species in the finch terest is focused on the vocalizations of genus Estrilda. the male foster parent. The parasite evi Such species-to-species relations can dently disregards the songs of any other be understood only if one assumes that species of bird; as a result, when it a long time ago the widow birds began reaches maturity, it is able to reproduce to arise from a single viduine prototype its host's sound patterns exactly. Al species that had started to parasitize a though the female parasite does not sing, single species of estrildid finches. When she becomes similarly song-imprinted, this ancient estrildid species began to and a memory of the host's repertory re evolve into several species, the widow mains with her for life. The imprinting birds were forced to follow suit, because becomes evident when ovulation takes only by doing so could they evolve place and the female's sexual drive is mouth markings sufficientlylike those of aroused. Once the female widow bird is the evolving new species of potential in search of a mate, she "knows" that the hosts. Of course, each widow-bird popu only appropriate male partner is one lation that failed to achieve such an who can recite the same calls and notes adaptive process was destined to become she heard from her foster father while extinct, since its mismarked offspring she was still a nestling. Only when the would starve to death in the nests of hos courting male corresponds to this proto tile hosts. In this way the evolution of type will the female widow bird allow the adaptively successful widow-bird mating. species both parallels and reflects the ev Superficially it might seem that the olution of their chosen hosts among the male's signal is merely a kind of lure, numerous species of estrildid finches.

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The sequence of e()ents in the nervous system, that coordinates the movements of the eyes and the head in fLrating a visual target has been clarified by recent experiments with monkeys

by Emilio Bizzi

ow the central nervous system triggered by the sensory components of tics of the motor p rograms underl ying H produces coordinated motor out its p redecessor. Thus, to use Sherring the orderly sequence of eye and head put has long been one of the ma ton's words, "coordination is in p art the movements in monkeys, and we have jor p roblems of neurophysiology. What compounding of reflexes." shown how reflex sensory feedback, gen accounts for both the g raceful p erform At the other extreme some investiga erated by the turning of the head, inter ance of the trained athlete and the ordi tors hold that the nervous system already acts with the centrally initiated programs nary, but hardly less remarkable, move incorporates all the information neces and thereby gives rise to "coordinated" ments of everyday life? For movement to sary for the selection of the muscles in eye-head movements. be coordinated an appropriate set of volved in a g iven movement and the se Consider the eye and head movements muscles must be selected, each of the quential activation of those muscles. The that follow the unexpected p resentation contracting muscles must be activated in motor system is viewed as a network of a visual target. In man and monkeys the proper temporal relation to the others capable of p laying stored p atterns in a the appearance of a target in the visual and a p recise amount of inhibition must predetermined manner following the field is usually followed by an orderly be delivered to each of the muscles that presentation of an adequate input. In in sequence of such movements. First, a will oppose the intended movement. In vertebrates, for example, the work of fast eye movement (called a saccade) addition to triggering the contraction of Cornelis A. G. Wiersma, Donald Ken carries the most sensitive p art of the a g iven set of muscles the nervous sys nedy and Donald M. Wilson has shown retina, the fovea, to the image of the tar tem must monitor the effects of its com the importance of central, built-in mech get. Second, after a delay of between 20 mands; it must have a way of coordinat anisms for the g eneration of motor p at and 40 milliseconds the head turns in ing movements of the various body parts; terns. the same direction. Since the eyes have it must be able to decide when to termi In vertebrates, however, and p articu moved first,and with a hi gher velocity nate a g iven p hase in a motor sequence larly in mammals, the contribution of than the head, their lines of sight reach and proceed to a new one, and so on. centrally p rogrammed p atterns of motor and fixate the target while the head is For three-qualters of a century, dating command and their possible modification still moving. Then for the duration of the back to the early studies of Charles Scott by feedback coming from p eripheral head movement the eyes maintain their Sherrington, investigators have held dif sensors is still a matter of speculation. target fLxation by performing a rotational ferent views concernin g how temporally Hence neurophysiologists are still faced movement that, by being counter to the patterned sequences of neuromuscular with the vexing question: What is the movement of the head, allows the fovea events are p rogrammed by the nervous role of peripheral feedback? Does it pro to remain constantly on the target it has system. Many workers have stressed the vide a signal to time the release of the just acquired. This maneuver is termed importance of sensory feedback in elicit next phase of a movement? Does it facili compensatory eye movement [see bot ing and coordinating a motor output. tate some aspect of the motor p attern? tom illustration on page 102]. The feedback is viewed as originating Does it maintain or complete the next To achieve this orderly sequence of with various types of sensors located in phase? Or does it add a new p hase to movements, that is, to direct the eyes the muscles, the tendons and the joints. tho!,e movements that were centrally and the head toward the target and ulti These receptors inform the central ner initiated? mately fixate the tar get with the fovea, vous system about various aspects of a the subject must make a number of com movement, such as its velocity, ampli n an attempt to answer such questions putations. To begin with, the subject tude and force. According to some in I we have been studying the coordina must compute the angular distance be vestigators, sensory feedback from each tion of eye-head movements in monke ys tween the initial lines of sight and the phase of movement is important in elic in our laboratory at the Massachusetts position of the target that is to be ac iting each subsequent motor output. Institute of Technolo gy. My colleagues qnired. Although we do not have a clear Therefore a coordinated motor p erform in this effort have been Johannes Dich understanding of how the angular dis ance could be described as being differ gans, Ronald E. Kalil, Piero Morasso and tance is computed by the cortical and entiated into many parts alon g the time Vincenzo Tagliasco. We have investigat subcortical visual areas of the brain, we dimension, so that eac h p art is reflexly ed the spatial and temporal characteris- do know that a signal corres ponding to

100

© 1974 SCIENTIFIC AMERICAN, INC he mono ds later t llisecon 0 m i is head me 20 to 4 ring th tina. So ion. Du f t he re e direct ated. part o tIle sam rget fix the tive ning in p the t a cted in gins tur to kee e condn head b e r rotate er b y th ES are gy key's counte record STUDI chnolo yes must ted to a ATION of Te nt the e ansmit vement ORDIN Institute moveme ing is tr Eye mo AD CO chusetts . When ead.turn 's head. YE.HE "Massa ted h ere nt of h monkey next E y at the illustra The amou ped to tion o n aborator pparatuS ts th e uS clam illustra thor's l ental a it attrac apparat ee t op ard. au experim sented, htweight graphY ( s as a rew of the nlY pre eye Ji� o.oculo f water the aid s sudde ence of electr drops o with wn) i ly sequ corded by gives not sho order ns is re s mouth al target ( train an ade, tur monkey' a visu sets in d a sacc Tuhe in tion a nd nt, calle i· p(fge). y's atten moveme ost s ens monke fast eye a, the m \01 ments. A the fove d move tered on and h ea is cen he target sO that t the eyes

© 1974 SCIENTIFIC AMERICAN, INC that distance is translated into both the oculomotor system and the head-motor system at about the same time. In fact, the electrical activity recorded from eye muscle and neck-muscle fiberss hows that motor commands are delivered al most synchronously to those muscl es. From this it follows that both t he oculo motor and the head-motor control sys tems must be making use of t he same angular-distance information at approxi mately the same time. As a result ampli tudes of eye and head movements are produced that are well correlated with the angular distance of the target.

e have shown that this finding is Wvalid in the case where a head movement begins from the straight ahead position and the eyes are centered in the head at the time the target is pre sented. Usuall , however, the e es wiII MEASUREMENT OF EYE MOVEMENT by electro·oculography takes advantage of the y y fact that the retina is positively charged and the choroid that lies behind it is negatively not be centered when a target appears. charged, even under resting conditions. The charges are kept separate by the external How, then, does the head-movement limiting membrane (the membrane of Bruch) that lies between the retina and the choroid. control system know the p osition of the As a result the resting eye acts as a dipole in which the cornea is some 10 to 30 microvolts eye in its orbit so that a p roper de positive with respect to the back of the eye. Eye position can be recorded by placing a pair gree of head-turnin g can be g enerated? of electrodes on the inner and outer corner of each eye (for horizontal movements) or The head-movement control system must above and below each eye (for vertical movements). When the eyes are aimed straight have access to eye-position information ahead, the potentials between similarly placed pairs of electrodes are balanced. Any rota· and then combine it with the angular tion of the eye, however, brings the more positive cornea closer to one electrode of each distance signal to achieve a coordinated pair than to the other. Resulting difference in potential serves as an index of eye position. eye-head movement. Information about 40 the p osition of the eye can be su pplied by sensors sensitive to stretching (mus if) cle spindles) located in the eye muscles w w or b internal monitoring of the oculo ex: 30 y of a number of sensor rece tors, tech 0 y p ::;; 10 nically referred to as proprioceptors. >-w w These include neck-muscle spindles, neck-tendon organs, receptors located in 0 the joints of vertebrae in the neck and rece tors located in the vestibule of the 30 p inner ear. All will g ive rise directly or if) indirectl to nerve im ulses whenever w y p w the head is turned. The uestion, then, is ex: q 0 10 compare the amplitude of the eye move ::;; ment in the acquisition of a tar get when 0 � w a monkey's head is allowed to turn and I when it is held fixed,we observe that the

0 amplitude of the eye movement is great 1< >1 er when the head is held fixed [see illus 100 MILLISECONDS tration on opposite page]. Clearly the

COORDINATED EYE·HEAD RESPONSE to the sudden appearance of a target is shown in amplitude of eye movement must be less five superposed tracings. The vertical scales indicate the amplitude of each movement in when the head is free to turn if an over degrees starting from the straight.ahead position. The eyes make an initial saccade of some shoot of the target by the combined eye 30 degrees, then counterrotate as the head begins turning toward the target. As a result head movement is to be prevented. when the head is fully turned, the eyes are once again pointed nearly straight ahead. Given this experimental observation,

102

© 1974 SCIENTIFIC AMERICAN, INC we must next ask what mechanism is re ity initiated by the head movement, let One can easily observe such eye sponsible for the modulation of saccadic us turn to the question of why this reflex movements induced by head movements amplitude. Two hypotheses can be con adaptive arrangement is more advan by asking a friend to fixate a visual tar sidered: Either the program responsible tageous to the animal than one based on get and turn his head from side to side for fast eye saccades is modified every a centrally preprogrammed modification while maintaining fixation. You will see time the head is ready to move or reflex of saccadic parameters. Clearly the reflex that, as his head moves, his eyes rotate activities initiated by the head-turning mode of organization g reatly simplifies in an equal and opposite way so that itself apply a corrective action to the the task of the motor-programming sys they remain on target. Such compensa ongoing centrall y pro grammed saccade. tems required for eye-head coordination. tory eye movements can be extremely Our experimental evidence supports the The eye and head movements can be rapid. Try fixating y our index finger second hypothesis. We find that afferent, programmed independently, since the while rapidly turning your head, and or incoming, signals arising from the vestibular system "automatically" nulli then move y our index finger with e qual sensitive receptors in the vestibule of the fies any displacement of the fovea from rapidity while keeping y our head mo inner ear are solely responsible for mod the target as a result of head movement. tionless. In the first case the vestibular ulating the saccadic amplitude. The ves Furthermore, by relying on vestibular system q uickly moves the eyes in the tibular impulses responsible for modula reflexes that monitor the actual move direction opposite to that of head move tion of eye movements originate when ment of the head, the resulting adjust ment and the tar get is seen clearly, but the cupula (a g elatinous cup into which ment of eye movements will be able to in the second case the slower visual cor hair cells protrude) in the semicircular compensate for all the unpredictable rective loop to the eye muscles cannot canal is deflected by movement of the peripheral loads and resistances that compensate for the movement of the endolymph (the fluid in the canal). These might change the course of the centrall y target. The target is consequently re impulses are first transmitted to nearby initiated (intended) head movement. duced to a blur as the eyes try in vain clusters of nerve cells, the vestibular nu The modificationof saccade charac to match its velocity. clei. From there, by way of direct and teristics is one aspect of the interaction Compensatory eye movements have polysynaptic pathways, they impinge of central programming and reflex activi been studied by several investigators. on nerve cells of the oculomotor nuclei. ties. Although this interaction plays a de Although it is generally agreed that such Positive evidence of the crucial role of cisive part in the process of target acqui eye movements are strongly influenced the vestibular afferent signals was dem sition by a combined eye-head move by visual and vestibular reflexes, includ onstrated in monkeys by surgically in ment, the role of feedback from p eriph ing feedback signals from various pro terrupting the pathway linking the ves eral sensory organs (vestibular and neck prioceptors, it has been hypothesized tibular receptors to the vestibular nuclei. afferents) extends beyond saccadic mod that compensatory eye movements are For several weeks after the operation ulation to control and g enerate compen initiated centrally and hence are not pri (before the monkey had learned to com satory eye movements. marily dependent on feedback informa pensate) the saccade amplitude during tion. In our own recent work we have head-turning was identical with the sac ince the eyes move first and with a found no evidence for central initiation. cade amplitude in the absence of head S higher velocity than the head, their We have been able to demonstrate, how movement. This resulted in a remarkable lines of sight reach and fixate the target ever, that compensator y eye movements overshooting of the target because the while the head is still movin g. Then for result from the reflex action of the ves unmodulated eye movement was simply the duration of the head movement the tibular system. As a conse quence of the added to the head movement [see mid eyes maintain their fixation by executing head movement vestibular receptors are dle illustration at top of next page J. a compensatory rotational movement stimulated, and their activity induces a Having established that saccades are that is counter to the movement of the compensatory eye movement that en adjusted in scale by the vestibular activ- head and compensates for it. ables the fovea to remain fixed in relation

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HEAD·FIXED AND HEAD·FREE RESPONSES to a suddenly ap· tion is achieved by a combined movement, labeled "gaze," that pearing target are compared in two sets of traces. When the mon represents the sum of the eye saccade and the head movement. No· kay's head is held fixed, the eye saccade must do the entire job of tice that the initial saccade is smaller in the second case because fixating the target (le!t). When the head is free to turn (righ(l, fixa· the turning of the head accomplishes part of the shift in the gaze.

103

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ROLE OF SENSORS IN ll'il'iEI1 EA R in the coordination of eye· middle show what happens when a monkey is presented with a head movements was demonstrated in the author's laboratory by similar visual target 40 days after surgical removal of its vestibular studies in which the vestibule of the inner ear of monkeys was apparatus. Since the initial eye saccade is uncorrected as the mono surgically inactivated. The set of tl"ee traces at the left shows how key begins turning its head, the monkey's gaze strongly overshoots a normal monkey shifts its gazc to a target by combining eye and the target. Even in this short period, however, some degree of head movements. Motion receptors in the inner ear initiate feed· compensatory eye movement has already developed. Traces at the back signals that modulate the amplitude of saccadic eye move· right were made 120 days after surgery. Now, even without the help ments and help the eyes to compensate, that is, counterrotate, of vestibular feedback, saccadic eye movements have been "recali· smoothly as the head turns tO\\ .rd the target. The traces in the hrated" through experience, so that the gaze no longer overshoots.

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DIFFERENT STRATEGIES of eye.head coordination appear in (L) simultaneously cease. A monkey uses a different strategy in the different behavioral contexts. Whenever a visual stimulus is sud· coordination of eye·head movements, however, when it turns denly presented to a monkey (left), the animal first turns its eyes, toward a given position in anticipation of the appearance of 8 then its head, in the direction of the target, which in this case ap· similar target (right). The author calls this mode "predictive." Now pears 30 degrees to the ri ght at eye level. The arrow indicates the the head begins to move before the target appears and before the time of target presentation. Trace R shows the burst of impulses start of the eye saccade. Moreover, the head movement is instituted that signals activation of the neck muscle (the splenius capitis) by a gradual increase in the activity of the agonist neck muscles that turns the head to the right. Impulses in the antagonist muscles (R) and a decrease in the activity of the antagonist muscles (L).

104

© 1974 SCIENTIFIC AMERICAN, INC to a p oint in visual space while the head distinguishing among such modes to the is rotating. continuing research on the central con Save on Summing up, we are now in a position trol of movement. The second topic is to outline a realistic scheme for how related to the impressive capacity for Calculators movements of the eye and head are co functional reorganization that is dis Before you buy a calculator. check our prices ordinated when a visual target is being played by eye-head motor p rograms fol acquired. The coordination involves a lowing lesions in key structures such as sequence of events in which feedback the vestibular system. signals p rovide a closed loop, thereby Hewlett-Packard making p ossible the correction of errors oncerning the first to ic, it is well The utmost and ultimate in high quality, precision, p sophisticated calculators. Made in USA. (Beware [see illustration.on next pagel. The se C known that in p rimates there are of imitations.) uence be ins with the detection of a HP-35 Scientific. hand-held 4 memories q g several other modes of the coordination incl. charger target somewhere in the visual field. of e e-head movements, such as those HP-45 SCientific. hand-held 10 memories y incl. charger Motor p rograms involving the head and observed while the animal is tracking a HP-65 Scientific. hand-held 100 step programming the eyes are activated and respond by moving object or scanning the visual en HP-80 Hand-held for business, banking, finance. 10 memories sending impulses to eye and neck mus vironment. In our laboratory we have HP-70 Hand-held for business and finance. cles. This results in a saccadic e e move recentl anal zed a articularl inter 6 memories y y y p y HP-46 Printing, Scientific. 48 functions, ment and a head movement that acti esting mode of coordination that we call 10 memories HP-46 Option 001, printing and display vates vestibular receptors, which in turn predictive because we observe it only combination HP-81 Printing for business, 20 memories. generate a compensatory eye movement. after the animal has memorized a set of fantastic HP-81 Option 001 combination printer and The compensatory eye movement allows reward contingencies and is able to make display the fovea to remain fixed in relation to a HP-81 Option 002 Printing with buffered an appropriate predictive movement that keyboard point in visual s ace during head-turn antici ates the resentation of a visual HP-81 Option 003 Printing, display and buffered p p p keyboard ing. The fixation allows a second visual stimulus. All calculators by HP carry one full year guaranty by HP. sampling, then a third and so on, with Under these conditions the timing of All HP hand-held calculators include charger, instruction manual, etc. opportunities for correcting errors at eye and head movements and the pattern each sampling. of neck-muscle activation are different If our hypothesized closed loop cor from those found in the visually tri g Texas Instruments rectl describes the coordination of eye gered mode [see bottom illustration on SR-lO Hand-held Scientific including charger y SR-ll Hand-held Scientific including charger head movements, it is clear that the role opposite pagel. In fact, during the p re SR-50 Hand-held Scientific (quantity limited, waiting period) of the motor p rogram stored in the cen dictive coordination of eye-head move SR-20 Desktop Scientific, 12 digits TI-2500 Hand-held, four functions with charger tral nervous system is simply to initiate, ments the head begins to move well be TI-1500 Hand-held with charger plus percent key in an im ulsive manner, movements of fore the saccade of the e e is initiat TI-2550 Hand-held with charger, MEMORY and p y PERCENT the e es and head. Since there is no cen ed. In addition the head movement is TI-2300 Desktop with constant, 10 large digits y TI·4000 Desktop. t2 digits with Full MEMORY tral programming of saccadic adjustment achieved by a g radual increase in activ TI-500 Printing electronic calculator TI-450 Desktop Scientific, very sophisticated and of compensatory eye movement, it ity of the a gonist muscles (the muscles follows that the functional, or behavioral, that initiate turning), which is accom coordination of head and eyes is the joint panied by a decrease in the activit y of Bowmar result of a central initiation (following a the antagonist muscles (the muscles that MX 100 Hand-held Scientific with charger MX 140 10 Digits SCIENTIFIC NOTATIONS. stored p rogram) modified by the crucial oppose turning). This p attern of recip Fantastic-with natural problem entry, calculating horse-power intervention of modulating signals trig rocal, g radual agonist-antagonist activity MX 90 10 large digits, dual memory, 8 functions, square root gered by receptors in the vestibule of the is in marked contrast to the bursts of MX 35 8 digits, hand-held, memory and % key inner ear. This conclusion somewhat sim muscle impulses invariably recorded Many other models. plifies our views of the neural mecha from the agonist muscles when a monkey nisms underlying motor coordination is p resented with an unexpected visual Kingspoint insofar as, contrar to common assum stimulus. y p SC-40 Sophisticated hand-held Scientific, multi tions, we find no need to postulate a spe The fact that motor output subservin g memories, parentheses, 10 digits plus 2 digits mantissa and 2 digits exponent cial central p opulation of "executive" the coordination of eye-head movements neurons with exclusive responsibility for is not fixed but instead exhibits distinc • coordinatin the e es and the head. tive atterns de endin on the s eCific Thousands of calculators. adding machines. type g y p p g p writers of all makes: REMINGTON. SMITH CORONA, So far I have described the timin g behavioral situation raises tantalizing VICTOR. COMPUCORP. ST. CLAIR. OLIVETTI. 3 M. ROCKWELL INTERNATIONAL. SONY TVs and and the characteristics of the coordina questions. For instance, are there sep Stereos. tion of eye-head movements that are arate areas in the brain for the program • elicited by the appearance of a visual ming of different modes of coordina Olympic Sales Co. is one of the largest. if not the largest distributor, of electronic calculators repre target, and have presented our evidence tion? If there are, are the various modes senting the best products on the market. Because we deal in volume we can pass the savings on to you. for the conclusion that the p rograms for of coordination subserved by a totally Call us before buying any kind of calculator. Call us e e-head coordination are not resent in different and se arate neural network? or write us and ask for our calculator catalogue so y p p we can give you the best possible deal. the central nervous system in their en How is the switching from one mode to tirety. In what follows I shall take up another accomplished? two additional and interrelated topics. These are formidable q uestions for OL'JmPIC SIlL&S comPlln'J.Inc. the neuro h siolo ist interested in out The first has to do with the fact that p y g 216 South Oxford Avenue there are other modes or programs of the lining realistic models for the various P.O. Box 74545 Los Angeles. CA 90004 coordination of eye-head movements in kinds of motor coordination. Neverthe Phone (213) 381-3911 • (213) 381-6031 addition to the one I have been discuss less, the investigation of such p roblems Telex 67-3477 ing, and I shall indicate the relevance of is no longer beyond reach. In fact, new

105 © 1974 SCIENTIFIC AMERICAN, INC techniques of recording from a single the distinction between strategies of Our results have shown that a variety cell in an intact trained animal such as movement is an aid in theinterpretation of several basically different mechanisms those developed by Edward V. Evarts of selective brain lesions of those struc are developed and jOintly brought into of the National Institute of Mental tures that are deemed important in the play. Among them are the development Health, combined with traditional neu regulation of these movements. of new eye programs, including one that rophysiological and behavioral ap provides compensatory eye movements. proaches, might enable us to unravel oncerning the second topic, we were We have already seen that in the normal some aspects of the patterns of motor ac C led to investigate plastic changes in monkey compensatory eye movements tivity in the cortical and subcortical areas the central organization of the eye-head are achieved by way of vestibular im of the brain. I believe the possibility of motor system by our discovery of the pulses. Two or more months after mon bringing different strategies of motor co decisive importance of the vestibular keys were surgically deprived of ves ordination u nder control in the labora input in determining the nature of the tibular sensors, however, centrally pro tory is relevant to the functional analysis coordination of eye-head movements. It grammed compensatory eye movements of the motor system. was natural to wonder how that coordi were found to contribute to ocular sta Thc notion of strategies of movement nation would be affected if the vestibu bility during active turning of the l1ead. is in fact a powerful tool for interpreting lar input to the brain stem were elimi Thus the oculomotor system is capable single-cell recordings from cortical and nated. Are there other mechanisms that of taking on, albeit in a crude and in subcortical motor areas. Since different can take over the vestibular function? adequate form, functions p reviously strategies of movement are characterized Our aim was not only to ascertain the elicited by vestibular activity. by different spatial-temporal patterns of degree of functional recovery of sensory Another mechanism contributing to commands to the muscles, more compel motor coordination but also to under the remarkable recovery in the cOOl·dina ling correlations between single-neuron stand the mechanism underlying the re tion of eye-head movements that occurs activity and some aspects of mo tor be covery of the coordination of eye-head within the firsttwo to three months fol havior can be established. In addition movements. lowing vestibulectomy entails a "recali bration" of saccadic eye movements with respect to visual input. As I have indi 1 2 cated, immediately after vestibulectomy the gaze of a monkey whose head is free to turn will badly overshoot a visual tar get because the saccade amplitude is no ACTIVATION OF HEAD longer modulated by corrective feedback AND EYE·MOTOR PROGRAMS SACCADIC EYE MOVEMENT signals from the vestibular apparatus. In AND IMPULSIVE COMMANDS > AND HEAD MOVEMENT TO EYE AND NECK MUSCLES other words, the eye movement appro priate for fixating the tar get when the head is held fixed is simply added to the head movement. After two to three months, however, vestibulectomized monkeys learn to make saccades that are smaller than nor

ACTIVATION OF mal as they turn their head in the direc ERROR t VESTIBULAR SIGNAL tion of a visual tar get, thereby reducing RECEPTORS I t the tendency of the gaze to overshoot its mark [see illustration at right at top of page 104]. On the other hand, if the 4 3 head of a vestibulectomized monke y is restrained when it is unexpectedly pre sented with a visual target p erhaps 30 degrees away from its straight-ahead axis SACCADIC ADJUSTMENT ANALYSIS OF VISUAL of vision, its eyes will continue to make AND COMPENSATORY EYE INPUT AND COMPUTATION 30 MOVEMENT TO MAIN· a saccade of degrees, enabling it to OF RETINAL ERROR < TAIN FIXATION fixate the target. Hence the oculomotor system is recalibrated selectively: when the head is restrained, the saccades are normal; when the head is free to turn, the saccades become smaller. These two oculomotor functions are an important p art of the mechanism un CONTROL SCHEME FOR EYE-HEAD COORDINATION is believed to begin (1) with a derlying recovery of the coordination of central.nervous.system motor program that initiates the movement of the eyes and head eye-head movements. They provide a when a visual target appears unexpectedly. The initial saccadic eye movement and head striking exam le of the remarkable plas movement (2) are evidently based on a rapid computation of the target location carried out p by cortical and subcortical regions of the brain in a manner not yet understood. As the ticity of the central motor apparatus, a head begins to turn, sensitive motion receptors in the vestibule of the inner ear initiate plasticity that comes into play whenever signals that lead to counterrotation of the eyes in order to maintain fixation of the target the organism is forced to compensate for (3). During these coordinated eye.head movements the visual input is analyzed and an a handica p or deficitim posed on it by error computation is made (4). The result is an error signal that closes the control loop. events over which it has no control.

106

Notes and observations from IBM which may prove of interest to the scientific community.

Dr. Alec Broers examines an X-ray image-forming device with the new low-loss scanning electron microscope.

Exploring An Invisible Realm

. With their incredible densities, ers to see surface details as small as 10 Yorktown Heights, N.Y. computer componcnts are rapidly ap angstroms-or a few atoms wide-on Whatever the eventual applications proaching dimensions no longer visible many objects. of their development, both Drs. Wells with even the best of optical micro Among the samples being examined and Broers agree that, in areas from scopes. Now, two IBM scientists have are specimens ranging from blood cells medicine to metallurgy, "This new low made a major advance in electron op to minute electronic components to the loss electron method gives us a chance tics, a key to further technological prog experimental X-ray image-forming de to examine the world around us, to dis ress. Dr. Oliver Wells and Dr. Alec vice pictured above, a development be cover what was perhaps unknown be Broers have developed a new method ing pursued by Michael Hatzakis and fore." for operating the scanning electron Dr. David Sayre, also members of the In a conventional surface scanning microscope which may allow research- Thomas J. Watson Research Center in microscope, now a standard research (Continued 011 Page 2)

Invisible Realm ... New Aid to Medicine (Continued from first page) At the Texas Institute for Re- ments can be shown in a number tool, a beam of electrons scans a speci habilitation and Research in Hous- of ways-the contour map of the men. Secondary electrons are ejected ton, scientists are using an IBM body pictured above, or cross from each point on the surface as the -- computer to pro- =Sr, sections of the body, or beam moves back and forth. At the (�\) 1II,l a duce highly accu- graphs showing how body same time, a spot is scanned across ' \ : rate, three-dimen- '%>:11 volume is di stributed cathode ray tube. The strength of the - \�� , �. s iona I mea sure ��r;; � from head to foot-to as- ejected electron signal controls the ments of the human �. (,I��- I" � ;" sist doctors in their diag- brightness of the CRT beam, resulting body for studies ranging �I nosis and treatment of a in a picture of the surface under study. from spinal deformities in chi!- II wide variety of medical dis- The microscope's resolution, or abil dren to weight loss in astro- orders. Three-dimension�1 b�dy ity to clearly distinguish smalle r fea nauts. II11\\\![I 0 measurements also provide Im- tures, is limited because the specimen Overlapping photographs of \ I\��"hI/fJ? � portant data for the automatic must be focused as much as a centi the body are taken simultane- fabrication of artificiallimbs. meter from the electromagnetic lens to ously. Then a plotting device, ,,�,�;y-� Dr. R. E. Herron, dlrec- collect electrons efficiently. like the type used in aerial �'1 ,)(((r(({� tor of the Institute's Bio- In another type of standard micro mapping, identifies reference � � '" �J stereometrics Laboratory, scope-called a transmission microscope points common to each photo 101 says: "The new method to create a three-dimensional �\j� makes it relatively easy for image. These reference points, \\JJ\ a physician to measure a which can number over 40,000, "-.. q child's growth pattern. Using are fed into the computer to pro- the computer-generated duce precise measurements of the measurements, he can determine any entire body or any part of it. With a deviation from the normal range as part computer driven plotter, such measure- of a routine physical examination."

The Future of Venice

A study team with members drawn Research Council is collecting data the from the IBM Scientific Center in study partners can incorporate into a Venice and Italy's National Research computer model of the problem. With Council is preoccupied-as are many a mathematical substitute for the ,real people-with the future of Venice. situation, team members can test dif Aqua Alta, or high water, is a phe ferent theories and hypotheses. nomenon that plagues the City of One paradox has already been re Canals. A product of storms in the solved: Venice is sinking because water Adriatic, Aqua Alta floodsthe Venetian is disappearing beneath it-drawn off lagoon many times each year. The by the fresh-water wells which supply Resolution is higher in the low-loss problem is further complicated be a nearby industrial area. scanning microscope because a shorter cause the lagoon bed on which Venice It is not likely that the sinking will focal-length lens can be used. rests is sinking year by year. soon stop, or that Aqua Alta will cease a To study the complex interaction of to be a threat. But the study is giving -objects can be placed as close as wind and water and tides, a seagoing scientists a clear analysis of the forces tenth of a centimeter to the lens. But laboratory belonging to the National at work on Venice. because in this case the electrons pass right through the specimen to form the picture, only thinly-sliced samples can be examined. Drs. \Nells and Broers have com bined the two techniques so that the surface of solid samples can be seen with extremely high resolution. \Vhile the sample is placed in the same posi tion as in the transmission microscope, the key difference in their development is the use of low-loss electrons-original electrons from the beam that lose very little energy on striking a solid surface. Low-loss electrons which bounce off the sample surface are pulled back by the lower half of the lens and are col lected to provide the output signal. The new electron microscope has been in its present form since the Spring of 1973, although it had gone through several stages of development before that time. It is currently capable of use ful magnification up to 300,000 times.

How can you log a forest without causing soil erosion and dwarfism or destroying the atmosphere for campers, hikers and fishermen? Up until recently clear-cut answers have not always been available-not only because of the com plexity of forest ecosystems but simply because trees do not grow fast enough for controlled experiments. Now with the help of a computer simulator one can "grow" a two-and-a half-acre portion of a forest at the rate of a year a second and immediately see the effects of a wide variety of sim ulated conditions. This development, according to one of the originators, allows research studies to be made which would ordinarily require cen turies in an actual forest. The project developed out of a co operative effort between the Yale Uni versity School of Forestry and Environ mental Sciences and IBM's Thomas J. Watson Research Center in Yorktown Heights, New York. Dr. Daniel B. Ecologists collected millions of measurements, everything from soil Botkin, a Yale ecologist and two IBM structure to water analysis, for original computer model. researchers-Dr. James R. Wallis, a hy drologist and Dr. James F. Janak, a Ecosystem site in the White Moun One of the most enthusiastic users theoretical physicist-worked together tains of New Hampshire, which con of the forest simulator approach has on a mathematical model for forest tains 13 different species from sugar been a multi-university research project growth to simulate environmental fac maple and white birch to mountain on the West Coast funded by the fed tors and various properties of each of ash and red spruce. They then worked eral government. Scientists there, along the tree species in one ecosystem, so up a number of relatively simple equa with researchers from Washington that hypotheses about the interactions tions to represent many of the inter State's Department of Natural Re could be made and tested. related conditions which affect the sources, hope to adapt the forest model Dr. Botkin and others collected the growth rate of a tree-soil quality, cli to the entire western region from original data at the Hubbard Brook mate, topography of the plot and com Alaska to Southern California. petition from other trees. It is possible in the not-too-distant These key equations were included future that foresters will be using the in the subroutine, Grow, along with computer on an everyday basis to plan two other subroutines-Birth and Kill. reforestation of land swept by fire or These took into consideration the an clear cut by loggers. In that event the nual growth increment for each tree, computer will be able to furnish such random planting of new saplings and information as how many trees to plant, killing off of other species to reflect which species, and how often they the cumulative effect of weather, plant should be thinned-all depending on succession and competition. the particular ecosystem of the region. While the original model deals with America's forests are one of our most a limited number of variables, it has valuable natural resources. With com the capacity to handle an infinite num puter simulation, the best conditions ber. Pollution, insect infestations-even for maximizing the growth of our for the rate at which deer nibble young ests can be determined more accura tely. systems." Dr. Wallis notes: "While the pres ent simulator reflects conditions of a forest in New Hampshire, it is espe DP Science Dialog is concerned cially adaptable to many other eco with topics which may prove of systems. interest to the scientific commun The computer model developed by ity. Your comments and sugges the three scientists is the first of its kind. tions are welcome. Just write: Other computer programs have simu Editor, DP Science Dialog, IBM lated simpler patterns of growth and Data Processing Division, 11 33 development-projecting, for example, Westchester Avenue, White productivity in a corn crop-but none Plains, N.Y. 10604. before had been able to reproduce the major characteristics of a system as complicated as a multi-specied, mixed age forest.

Geological changes in the level of the Mediterranean shoreline have

sublnerged a nUlnber of classical sites. The investigation of one of

these shallow-water ruins suggests that they wouLd all reward study

by Michael H. Jameson

he introduction of self-contained the shoreline of a sheltered circular har tion of the ruins of Halieis, which lie in underwater breathing apparatus bor that was smaller then than it is to and around the modern town of Porto Tsome 20 years ago opened up the day. The settlement was called Halieis, Cheli [see bottom illustration on page new domain of underwater archaeology. or "the salty places," probably because 113]. Tracing the line of the ancient city Now it seems that certain geological nearby sea-level Rats were used as salt walls down to the water's edge, we soon events of the past open up an extension pans. The population of Halieis probably found that a considerable part of Halieis, of that domain into what can be called never exceeded 4,000; the inhabitants some four and a half acres in extent, was shallow-water archaeology. So far the presumably supplemented their agricul now submerged in the harbor. The depth principal beneficiaries of this kind of tural resources, meager in this arid pe of water over the ruins ranged from a archaeology have been students of clas ninsula, by fishing, exporting salt and few inches to more than 10 feet. As we sical Greek and Roman times. The rea dealing in the valuable purple dye of were to learn later, another 40-acre area son is that the sites that have been in antiquity that came from the marine outside the city walls was similarly cov vestigated are all in the Mediterranean snail MUTex, which was plentiful in their ered by the harbor shallows. area. waters. To a dry-land archaeologist a drowned The shoreline of the Mediterranean About 470 B.C. the town opened its site seems at first a total loss. Actually it has had its geological ups and downs gates to a company of refugees from has certain compensating advantages. over the past few thousand years. For Tiryns, a neighboring principality that For one thing, wood and other organic example, the ruins of the port of Ephesus had been overrun by forces from the materials are better preserved under wa in Turkey today lie some miles inland larger city-state of Argos. The new ter than on land. Furthermore, Halieis, from the coast. An even more dramatic comers seem to have invigorated Halieis. like most such cities, was built mostly of example is the Temple of Serapis at an For most of the next two centuries the sun-dried mud bricks that were set on cient Puteoli, near Naples. The temple port, protected by a system of walls and stone foundations. On land when such now stands, as it did when it was built, a hilltop citadel, served as a valuable buildings fall into ruins, the mud brick on dry land. High up on its stone col naval base during a period that wit eventually melts away, and as often as umns, however, are numerous holes that nessed continual struggles among the not the foundation stones themselves are were cut into the stone by burrowing larger Greek powers. Then, sometime later stolen to be used in other construc marine animals; evidently the temple after the death of Alexander the Great tion. At Halieis submersion had protect was once submerged for a considerable in 323 B.C., Halieis was 'mysteriously ed many of the foundation stones from length of time. abandoned. thieves, and at the same time, wave ac My own acquaintance with shallow tion had swept away such remnants of water archaeology began at a site in Beginning in 1962 my department at the mud-brick superstructures as had not Greece. At the beginning of the classical the University of Pennsylvania, the already been broken down by rain. To Greek period a small city-state arose near Department of Classical Studies, under clear the debris from a comparable area the tip of the Argolid peninsula in the took with the support of the University on land, using normal archaeological Peloponnesus. The town grew up along �'1useum a conventional dry-land excava- methods, would take years of work, whereas in the harbor, under the right conditions, entire sections of the city lay waiting to be revealed. The question was how. The octopus SANCTUARY OF APOLLO, built outside the walls of ancient Halieis, is seen in the aerial photograph on the opposite page. Constructed on what was at the time a harborside site, the fisherman who slowly sculls across the sanctuary was later drowned by subsidence. Many of the foundation stones of sanctuary harbor at dawn knows how to find the structures escaped later reuse because of their inaccessibility under water, making the orig. large blocks of stone in whose crevices inal ground plan relatively easy to reconstruct. Out·of·focus object leading to the small boat his quarry hides. The shallow harbor wa is the tether for the balloon that suspended the remotely controlled camera above the site. ters, however, are made murky by rich

til

© 1974 SCIENTIFIC AMERICAN, INC organic growth and are easily rendered altogether opaque by wave action. Only occasionally does the combination of a flat calm and sunlight at the right angle provide a glimpse of the drowned streets and houses. Indeed, most of Porto Cheli's inhabitants had no suspicion of what lay just below the harbor surface. In 1967, following an earlier season of snorkel surveying, our group at Porto Cheli was joined by a team from Indiana University. The work load was divided; we would be responsible for the shallow water research and the Indiana team for the work ashore. Julian and Eunice Whittlesey provided the perspective we needed for our endeavors by suspending a camera from a tethered hydrogen bal loon, which a swimmer would guide into position in the early-morning hours when the harbor was at its calmest. The very first roll of film showed us a detail of the drowned city wall, the outline of one of a pair of towers, that we had not been able to make out because we had been too close to it in the shallow water. The Whittleseys' balloon-supported camera has provided similar insights for five sea sons now. CONTROLLED EXCAVATION under water was achieved by placing a square frame, Our shallow-water work in both 1967 mounted on adjustable legs, over each intended trench. Here a diver is seen adjusting the and 1968 was concentrated on recover horizontal orientation of a frame with a carpenter's level. The position of each two·meter· ing the plan of the drowned part of Ha square frame was noted with respect to the overall site grid, and its depth below sea level was determined. As the excavation under each frame progressed the location of uncovered lieis by a combination of surveying and artifacts was recorded with respect to both horizontal coordinates and vertical position. utilizing a high-pressure water jet to clear away the silt and sand that ob scured many of the foundation stones. The motor, pump and hose for the water jet we kept aboard a chartered local fish ing boat. The boat's owner, an octopus fisherman, took us across the harbor one day and showed us a large complex of drowned buildings that he had located in his fishing. The complex lay about half a mile from the main gate in the city wall, and its presence had not been sus pected up to that time. The Whittleseys promptly made balloon photographs that gave us some notion of the extent of the new find. We left Porto Cheli deter mined to survey the complex in the near future and if possible to excavate it.

When we returned in 1970, we carried with us new means of clear ing away bottom debris: light, portable dredges that had originally been devel oped for gold miners and that had al ready proved to be particularly useful in shallow-water work undertaken by ar chaeologists from the University of Chi cago and Indiana University at Ken chreai on the Isthmus of Corinth. The pump for each dredge, which we mount

FOUNDATION PLANS were prepared by noting the size, shape and position of each of the ed on a scaffold near the shore, sent a foundation stones on waterproof paper. Here a diver, having measured a stone, sketches its stream of seawater through a hose to the position on a sheet that already shows the location of foundation stones surveyed earlier. working head of the dredge. The head

112

© 1974 SCIENTIFIC AMERICAN, INC was a galvanized iron pipe; the pumped water entered the pipe at a 45-degree angle, producing a powerful suction at the rear of the working head. This part of the apparatus was kept 100 feet or so away from the area under excavation in order to avoid having the discharge wash back and obscure the excavator's vision. Lengths of quick-clamping irrigation pipe led from the dredge head to the work area; the last length of the suction apparatus was made of corrugated rub ber, thus allowing the excavator flexi bility of movement. The diver could feed mud, small stones and any plant debris that he freed from the bottom into the rubber tube; the suction promptly de �osited the waste materials a good dis tance away. As an added benefit the suction also continuously drew offthe obscuring silt that clouded the water as a result of a diver's least motion, so that the area being excavated remained rela tively clear. We began work at the complex by es tablishing over the target area a su b merged grid of 10-meter squares that ANCIENT HALIEIS stood near the southern tip of the Argolid peninsula, a region of the was tied into the Greek ordnance survey Peloponnesus roughly equidistant between Athens and Corinth. Today its sheltered harbor grid ashore. The intersections of the grid is the site of the modern town of Porto Cheli, where few knew of the drowned ruins. lines were marked by nails, each iden tified by colored flagging, driven into the harbor bottom. The grid provided a framework for the stone-by-stone plan of all the foundations in the complex and also fixed the location of the various trenches we intended to excavate in or der to sample the stratigraphy of the site. Stratigraphic excavation is, of course, the sine qua non of all archaeology. It requires the removal of successively deeper layers of earth and the assign ment of the artifacts discovered in each layer to a general time interval. Often the excavator's downward progress is dictated by minor variations in soil tex ture and color that, for example, make possible the detection of intrusions from above, such as storage pits or the founda tion trenches for later walls, which may cut into older strata. In shallow-water excavation all these considerations can be taken into account, although detec tion of soil differences is more difficult and allowance must be made for dis turbances in levels caused by the incom ing water. The uppermost level of mud and sand under water corresponds to the disturbed plow soil of a cultivated field on land and needs to be cleared before the significant levels in a trench are reached.

Over each proposed trench we fitted SUBMERGED PART of the harbor at Porto Cheli today that was dry land during the first an iron frame two meters square, secured millennium B.C. is the area between the innermost contour line (w hite) and the present in position by a two-meter leg at each shoreline (color). A considerable part of the city wall and the settlement within it (bottom) comer. The frame was free to ride up or was thus preserved, as were traces of the road from city to sanctuary and much of the sanc down on the legs. The legs in turn had tuary complex (right of center). A plan of the sanctuary appears on the next two pages.

PRINCIPAL COMPONENTS of the sanctuary of Apollo are (from tions of an open·air altar (d) that stood between the starting line left) "grandstand" foundations (a, b) to the east and west of the and the front of an early three·chambered temple of Apollo (e), near end of a footrace track; one track starting line (c); founda· with an entrance porch (f); massive foundations of a later, more

been set up in a known position with with respect to the frame's edges is mea four vertical trench faces and for analyz respect to the overall grid system. The sured and recorded (on a waterproof ing the finds. frame was made horizontal with the help form that bears a scale drawing of the As we surveyed the site, sluicing away of a carpenter's level, and its depth below frame) and its vertical position is de mud and sand from the foundation the surface, which we called its negative termined by dangling a plumb bob from stones and digging test trenches here and elevation, was determined. This required a movable bar on the frame and measur there, the character of the structures that placing the bottom end of a stadium rod ing the distance from the bob to the bar had once stood between the edge of the on the leveled frame and then taking a with a meterstick. The object is then put harbor and the ancient coast road lead reading on the part of the rod that pro in a plastic bag with a numbered tag, ing to the main gate of Halieis gradually jected above the water, using a transit and the same number is recorded on the became clear. They had formed a sanc set up at a known elevation on the shore. waterproof paper next to its indicated tuary outside the city: a large open-air The frame method and the excavation position. Large objects such as roofing altar for animal sacrifices, a temple to procedures associated with it, mainly de tiles and rubble are not bagged but are shelter the deity in whose honor the sac vised by James A. Dengate, were in put in tagged baskets for later examina rifices were made, various auxiliary genious adaptations of techniques that tion ashore. Potentially perishable ob buildings and, quite unexpectedly, a had been developed under other circum jects such as those made of wood or met runners' racecourse that must have been stances. Each diver worked from one to al are freed of most of their salt content built for the quasi-religious athletic two hours at a time, no more than twice by immersion ina tank of fresh water games so beloved of the classical Greeks. a day. Floating at neutral buoyancy un ashore and then are subjected to various der the frame, he would dig up the bot techniques of preservation. The diver Indirect evidence suggested that the tom with a small hand pick, a knife or types up his notes immediately on re sanctuary's deity was Apollo, the his bare hands. For the most delicate turning to shore, so that each three-diver prophet-musician son of Zeus who was work, where the excavator ashore might team's series of notes prOVides a consecu widely worshiped throughout Greece. use a small trowel or a brush, the under tive record of the excavation of the He is known to have been the chief god water excavator moves his hand back trench. One man from each team is re of Halieis, and his image often appeared and forth to establish a light current. sponsible for writing a final report on on the city's coins. Furthermore, in a When an object is located, its position each trench, for drawing sections of the treaty between Halieis and Athens, in-

METERS i I o 10

ambitious building (g) that probably replaced the early temple; those attending religious festivals, and a well (i) that held many foundations of a third building (h) that may have housed competi drinking cups. The southern starting line of the racecourse was tors in the games at the racecourse or served as dining quarters for only 167 meters away, making it one of the shortest in Greece.

scribed on stone in 423 B.C., the text that the first two elements in the future religious festivals or were used to house provides that another copy of the treaty complex were built. A narrow, south competitors in the games. The remains be erected in the sanctuary of Apollo at facing temple that measured 27 meters of many drinking cups, found in a nearby Halieis, so that we know he had a temple from end to end but only 4.46 meters well, would support either interpreta there. A marble statue found in frag from side to side was raised adjacent to tion. ments among the temple ruins points to a Hat stretch of shore suitable for foot All the later structures to the east of the same conclusion. A discovery made races and other sports. The outdoor altar the temple testify to the disadvantage during our second season resolved the was placed between the front of the tem of a site's not being sufficiently drowned. question beyond further doubt. The div ple and the racecourse. No doubt some They were built on higher ground and ers recovered the remains of three long primitive wood statue of Apollo looked were therefore more exposed than the pieces of angled iron, welded together out through the entrance of the temple, other buildings as the shoreline sank. It by corrosion [see top illustration on page overseeing both the altar and the race must have been all too easy to bring in a 118]. We identified them as a set of course beyond it. boat and load it with the largest and best three temple keys; in Greek art such keys At later times other buildings were blocks of stone. In any event we can are often shown in the hands or on the added to the sanctuary, farther to the speak only tentatively about what once shoulder of priests. In spite of the cor east and facing the altar_ A formal en stood in that part of the complex. In this rosion it was just possible to make out, tranceway was also built, leading from connection the original temple, which inscribed.at the top of one key, the name the coast road to the open space between was the earliest structure at the site and Apollo. the ..altar and the racecourse. Although was built of the simplest materials, is Today, after our third season of exca added buildings are regularly encoun also the best preserved; because it was vation, the history of the Halieis sanc tered at most Greek sanctuaries, their sunk the deepest it was the least pil tuary can be reconstructed in consider architecture is rarely specialized enough laged. Certainly a part of the original able detail. The harborside settlement to provide a clue to their function. Here temple survived into the fourth centurv that was to become a city-state started to the additional buildings near Apollo's B.C., when the city met its end. expand during the eighth century B.C., temple contained a series of small rooms. We found it possible to re-create many just as Greece in general was reawaken This suggests that the buildings provided details of the temple's original appear ing after its dark ages. It was at this time facilities for dining in connection with ance by studying the debris of the col-

115 © 1974 SCIENTIFIC AMERICAN, INC lapsed walls and roof. From the base roof was made of heavy tiles. Many of would have been indispensable for roast upward the temple walls were built of these were found where they had fallen ing the meat of sacrificed animals. Spits two rows of limestone slabs; as many as when the roof collapsed. Flat rectangular also served as a primitive form of money four courses of the slabs are still standing "pan tiles," 30 inches long, 20 inches that continued in circulation in near in some places. The slabs were roughly wide and two inches thick, were ar by Sparta long after conventional coin finished on their outer face only. Judg ranged side by side; the joints between age had been introduced elsewhere in ing by the heavy fall of masonry along adjacent rows were concealed under nar Greece. In addition to the spits we found the outer face of the walls their upper row, angular "cover tiles" some six 18 silver coins of various denominations courses may also have been stacked stone inches wide. Not all pan tiles and cover that had been minted between 550 and slabs rather than the more usual mud tiles are of the same size, shape and 525 B.C. on the island of Aegina (mod brick. In any event solid single blocks of fabric, a fact that suggests roof repairs ern Aiyina), which lies between Halieis stone ran through the width of the walls at intervals of many years. As a finishing and Athens. The coinage of Aegina was at the four corners. The lowest course in touch the temple walls were plastered widely circulated throughout Greece up cluded a narrow projecting ledge, and on on the inside and perhaps on the outside to the time of the island's subjugation by the inside of the building semicircular too. On the inside, at least, the plaster Athens in the middle of the fifth century pieces of limestone were set at 1.5-meter bore painted designs; the remains of the B.C. intervals. These bases were evidently the designs, however, are too fragmentary to Sunk into the floor of the temple trea supports for wood columns; the upper allow reconstruction. sury were two large masses of heavily part of the columns must have lent addi corroded iron. An X-ray plate of one of tional strength to the upper part of the The narrow temple building had a the masses shows the outline of two axe walls. porch at the south end, facing the al adze heads and one double-axe head. The temple floor was paved in places tar, and was divided into three cham Like the iron spits, these tools would with irregularly shaped slabs of sand bers. The front chamber would have have had some monetary value, but an stone, but in the main it was composed held a now vanished image of Apollo. other interpretation of their presence in of chunks of soft, clayey limestone that The broken marble statue we found the treasury is possible. One of my col formed a hard-packed layer. Round slabs there evidently represents a much later leagues, an Orientalist, tells me that in of stone stood along the main axis of the replacement. Between the stone base the ancient Near East the tools that were temple; these were evidently the bases for the statue and the rear wall of the used in the building of a temple were for a central row of wood columns that first chamber is a space that seems to often thereafter dedicated to the resident helped to support the roof. Considerable have served as a temple treasury. There deity; such may have been the case here. support must have been required: the we found quantities of iron spits, which Among other finds in the treasury area

- -- ...... -� ..", : .. •- --:- �. :. ;, " : . - - -co._ • .. .. ' .<1: ..' "" to' :-p_ 0_ " -

' . � . . . .� .�. / . �� ::'.�o<_:-:.- � . ' - - -. . . _ . . . .' . 0.:' ""' : "" ?-'" ...... _.' .. ' . - . � - . � : - -C> .' .; - . c, __" - - • -0" --- GO. _

ALT AR AND TEMPLE are shown in this reconstruction as they with heavy terra·cotta tiles, was supported by the walls and by may have appeared in the fifth century B.C. The temple porch has pillars along the walls and along the central axis of the building. been omitted. The temple walls were built of roughly dressed Animals were sacrificed to Apollo both on the plastered top of the stone and were smoothly plastered on the inside. The roof, covered outdoor altar and within the second of the three temple chambers.

116 © 1974 SCIENTIFIC AMERICAN, INC were some pieces of amber, eVidently imported from the Baltic, bits of ostrich eggshell imported from Africa and an inscribed bronze plaque made early in the fifth century B.C. Most of the inscrip tion is illegible, but the parts of the text that can be clearly read refer to the im b P position of fines. resumably the plaque a contained a warning not to misuse the temple treasures. The middle chamber of the temple may have served as an inner sanctum where oracular and purification rites were performed. The presence there of numerous horn cores from sheep or goats and the bones of young pigs is suggestive of such a ritual function. A shrine of Apollo on Crete and also one of Hermes there had altars made of piled-up horns; Apollo's altar of horns on Delos was known throughout classical Greece. Sim ilarly, the sacrificeof piglets was a com mon practice, particularly in a purifica tion context; that was how Orestes was 0. ,;., . purged of guilt in Apollo's celebrated � c shrine at Delphi after slaying his mother, Clytemnestra. Also found in the middle chamber were the heads and torsos of three bronze animal figurines: a goat, a ARTIFACTS recovered from the early temple include weapons made of iron (a), probably ram and a bull. The bronzes were de the offerings of well·to·do worshipers, and miniature wine cups (b), a common temple signed to fit as finialson the tips of wood offering of the poor. Silver coins (c) were found in the part of the first chamber that appears shafts, but their function is open to spec to have been a repository for temple treasure; they had been minted on the island of Aegina. ulation. The temple's third and last room was evidently a storage area. There we found the remnants of at least 5,000 miniature pottery wine cups, a common offering of the poor. Throughout the temple we also found knives, swords and spearheads of iron. These evidently represented the of ferings of people of greater means. The arrival of the refugees from Ti ryns early in the fifth century B.C. may have prompted certain temple renova tions. At about this time the old circular bases for the temple's axial row of pillars were for the most part replaced with rectangular blocks of a finer stone and some of the new bases were topped with circular plinths. The columns they sup ported, however, continued to be made of wood; no stone column drums have been found in the ruins. The positions of the new pillar bases make it plain that not all was well with the temple roof. They are located irregularly, probably wherever the sagging roof most needed support. Other changes perhaps inspired by the refugees from Tiryns include a new temple entrance, built from the porch into the forechamber and distinguished by a handsome stone threshold. It is tempting to see in a rectangular loop of STATUE OF APOLLO, found in fragments in the first chamber of the temple, imitates the iron found nearby the keyhole of a van sculptural style of the early fifth century B.C. but was actually made at some later date. It ished wood entrance door into which the may have replaced an earlier statue, possibly destroyed in an Athenian attack in 460 B.C.

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© 1974 SCIENTIFIC AMERICAN, INC to the late eight h century and early sev enth. In the more advanced parts of Greece at that time cult buildings as primitive as the Halieis temple were be ing replaced by the first of the Doric temples, built of well-cut masonry and surrounded by a colonnade of pillars. In the quiet backwater of Halieis, Apollo's old shrine was to be preserved for cen turies longer. Few objects found in the CORRODED IRON BARS, curiously bent, are the remains of three temple keys. It proved ruins, however, can be dated later than possible in spite of the corrosion to read the name Apollo inscribed on one of the keys. the middle of the fifth century B.C. We know from recorded history that Athens made an unsuccessful assault on great iron temple keys fitted and to iden used in the construction of the temple. Halieis in 460 B.C., and it may be that tify a second iron object as a door pull. After treatment for the effects of long the unprotected sanctuary by the shore That the people from Tiryns were in immersion a sample of the wood provid was damaged at that time. Whether or volved in these various innovations is ed a carbon-14 date (adjusted for corre not the Athenians desecrated Apollo's suggested by the fact that the letters on lation with tree-ring dates) of 780 ± 59 temple, it appears to have received little both the temple key and the bronze B.C. The date is indicative of the time attention thereafter. At some later time treasury plaque are written in the alpha the pine was felled. If we assume that a small building was constructed in what bet of the Argive plain, the Tirynthians' the construction utilized newly cut tim had been the temple entrance. Either be former home , and not in the alphabet in bers rather than reused ones, this range fore or after that (the chronology is still common use at this end of the Argolid of dates suggests that the temple was not clear') the marble statue we found peninsula. built in the period from the latter part of was placed on a foundation of reused the ninth century B.C. to the latter part of blocks in the outermost chamber and When was the temple of Apollo built the eighth century. The more recent date marble lustral basins were set on each and how long did it stand? We were seems the most plausible: the oldest pot side of it. The statue imitates early fifth able to salvage some of the pine timbers tery recovered from the ruins dates back century sculpture in its style but it was clearly made at a later time. The impres sion one has is that the old temple was now a kind of antique, damaged but not destroyed, that was being preserved more as a sacred relic than as a function ing religious building. Eventually, as we know from the condition of the timbers we recovered, the temple was destroyed by fire. Meanwhile the town of Halieis flour ished, and considerable money and en ergy were invested elsewhere in the sanctuary. The outdoor altar in front of the old temple was rebuilt on a grander scale, and four pillars were erected there, probably to support a canopy near one end. The blocks of fine, hard lime stone that composed the upper part of the rebuilt altar were almost all pillaged in later years for use elsewhere. Immediately to the east of the old temple a larger and more ambitious building was constructed. Like the re built altar, this modern structure was later robbed of much of its stone; today even its orientation is in doubt. I would guess that it was a new temple that faced the rebuilt altar in much the same way the old temple did, and that it was in tended to fill the same function. Its foun dation was massive: some of the stone blocks are three meters long. We assume that the building walls were made of mud brick because in the vi�inity we re covered heavy baked bricks: 30 inches X·RAY PLATE of one large mass of corroded iron found with the temple treasure reveals long, 20 inches wide and nearly four two axe·adzes and one double axe. The tools may have been used in constructing the temple. inches thick. These bricks were probably

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© 1974 SCIENTIFIC AMERICAN, INC used to make the top course of the wall MATERI ALS on which the roof beams rested. The roof RESEARCH itself was tiled, but the tiles differ in de sign from those used in the old temple. CENTER Wide and curved, they are of the type REPORTS .. known as Lakonian. The few artifacts On the worl d ' s largest we recovered from the ruins-wine cups n and iron weapons-are some support for extended-chai the interpretation that the structure was a temple. polymer The racecourse was also improved by the construction of a starting line at each crysta l s . end. The starting lines consisted of fitted stone blocks, one for each of the track's six lanes; parallel grooves indicated where the runners should place their feet and sockets allowed the mounting in each lane of a wood hysplex, or starting gate. The starting lines are 167 meters apart, which makes the Halieis stadium one of the smallest in classical Greece; a one-lap race would have covered little more than 180 yards, whereas the Olym pic stade was more than 200 yards. The existence of two starting lines allowed a one-lap race to begin at the city end and finish near the sanctuary altar and a two lap race to begin and end near the altar. Foundations were built for some kind of spectator accommodation on each side of the starting line at the altar end. We found the starting line at the city end of the stadium by probing along the east wall of the sanctuary until the wall end At the Materials Research Center Drs. R.H. Baughman and K . C. Yee ed; the line at the altar end was discov have syntheSized large polymer crystals which have extraordinary prop ered by accident when the discharge erties and unique internal structures. The crystals, which are formed by from one of our dredges exposed one of solid state reaction, have fully conjugated backbone structures. In addition the starting-line blocks. to previously known single chain polymers, they include two new classes The fate that befell Apollo's sanctuary of polymeric molecules designated "ring-bridged" and "cyclically-bound remains as unexplained as the fate of ladder" polydiacetylenes. In appearance, the crystals exhibit metallic Halieis itself. As far as we know the sea luster, intense coloration, and dichroism. They have negative macroscopic did not encroach on the sanctuary and thermal expansivities, very high strengths and are semi-conductors. the city until well after the beginning of Ordinary polymer crystals are microscopic in size and typically the Christian era. Before then, of course, consist of molecular chains folded back upon themselves much like minor changes in the height of the land ribbon candy. In contrast, Baughman's and Yee's new polymer crystals could have contaminated the local wells are up to 15 cm in length and consist of parallel, unfolded chains. Their with salt water and forced abandonment unusual properties are associated with the nearly perfect alignment of of the area. It is perhaps more likely that the molecular chains and the absence of gross structural defects. They are made by first crystallizing some powerful warlord, perhaps Deme the molecules of an appropriate monomer and then photopolymerizing the monomer crystal with ultra-violet light or trius Poliorcetes, the "Besieger of Cities," gamma rays. deciding about 300 B.C. to eliminate a naval base that might be used against Availability of large monocrystals provides a unique opportunity to him, destroyed the fortifications and explore the behavior of nearly defect-free polymeric materials. Funda drove out the inhabitants. mental understanding of the solid-state synthetic method has allowed template-like control of polymer structure t e levels: molecular, Halieis was a modest town with a on hr e crystallographic and morphological. This provides a capability for modest sanctuary. By an accident of geo syn thetic tailoring of polymers to optimize properties dependent upon molec logical change it has been possible to ular structure and crystalline perfection. study there aspects of a classical Greek city-state that are seldom accessible at Allied Chemical Corporation/MaterialsRe search Center

dry-land sites. In the course of the work, P.O. Box 1021R • Morristown, New Jersey 07960 methods of reconnaissance and of exca vation in shallow water have been ad vanced. Our experience suggests that many more rich opportunities for archae ology exist in the precarious zone be tween the sea and the land.

© 1974 SCIENTIFIC AMERICAN, INC Let us approach the voting paradox by first conSidering a fundamental defect MATHEMATICAL GAMES of our present system for electing offi cials. It frequently puts in office a man who is cordially disliked by a majority of voters but who has an enthusiastic On the paradoxical situations that minority following. Suppose 40 percent of the voters are enthusiastic supporters arise from nontransitive relations of candidate A. The opposition is split between 30 percent for Band 30 percent for C. A is elected even though 60 per cent of the voters dislike him. theory, one comes on a relation that one One popular suggestion for avoiding expects to be transitive but actually is such consequences of the split vote is to by Martin Gardner not. If the nontransitivity is so counter allow voters to rank all candidates in intuitive as to boggle the mind, we have their order of preference. Unfortunately what is called a nontransitive paradox. this too can produce irrational decisions. henever a relation R that ap The oldest and best-known paradox of The matrix in the illustration at the left Wplies to xRy and yRz also ap this type is a voting paradox sometimes on this page displays the notorious vot plies to xRz, the relation is said called the Arrow paradox after Kenneth ing paradox in its simplest form. The top to be transitive. For example, "less than" J. Arrow because of its crucial role in Ar row shows that a third of the voters pre is transitive among all real numbers. If 2 row's "impossibility theorem," for which fer candidates A, Band C in the order is less than 7Tand the square root of 3 is he shared a Nobel prize in economics in ABC. The middle row shows that anoth less than 2, we can be certain that the 1972. In Social Choice and Individual er third rank them BCA and the bottom square root of 3 is less than 7T. Equality Values (1 951) Arrow speCified five con row shows that the remaining third rank also is transitive: if a = b and b= c, ditions that almost everyone agrees are them CAB. Examine the matrix carefully then a = c. In everyday life such rela essential for any democracy in which so and you will find that when candidates tions as "earlier than," "heavier than," cial decisions are based on individual are ranked in pairs, nontransitivity rears "taller than," "inside of" and hundreds of preferences expressed by voting. Arrow its head. Two-thirds of the voters prefer others are transitive. proved that the five conditions are logi A to B, two-thirds preferB to C and two It is easy to think of relations that are cally inconsistent. It is not possible to de thirds prefer C to A. If A ran against B, not transitive. If A is the father of Band vise a voting system that will not, in cer A would win. If Bran against C, B would Bis the father of C, it is never true that tain instances, violate at least one of the win. If C ran against A, C would win. A is the father of C. If A loves B and B five essential conditions. In short, a per Substitute proposals for men and you see loves C, it does not follow that A loves C. fect democratic voting system is in prin how easily a party in power can rig a de Familiar games abound in transitive ciple impossible. cision simply by its choice of which rules (if poker hand A beats Band B As Paul A. Samuelson has put it: "The paired proposals to put up first for a beats C, then A beats C), but some search of the great minds of recorded vote. games have nontransitive(or intransi history for the perfect democracy, it The paradox was first recognized by tive) rules. Consider the children's game turns out, is the search for a chimera, the Marquis de Condorcet in 1785 and is in which, on the count of three, one ei for a logical self-contradiction.... Now known in France as the Condorcet ef ther makes a fist to symbolize "rock," ex scholars all over the world-in mathemat fect. Lewis Carroll, who wrote several tends two fingers for "scissors" or all fin ics, politics, philosophy and economics pamphlets on voting, rediscovered it. gers for "paper." Rock breaks scissors, are trying to salvage what can be sal Most of the early advocates of propor scissors cut paper and paper covers rock. vaged from Arrow's devastating discov tional representation were totally un In this game the winning relation is in ery that is to mathematical politics what aware of this Achilles' heel; indeed, the transitive. Kurt Coders 1931 impossibility-of-prov paradox was not fully recognized by po Occasionally in mathematics, particu ing-consistency theorem is to mathemati litical theorists until the mid-1940's, larly in probability theory and decision cal logic." when Duncan Black, a Welsh economist, rediscovered it in connection with his RANK ORDER monumental work on committee decision 2 3 D E F making. Today the experts are nowhere near agreement on which of Arrow's five conditions should be abandoned in the A B C A 8 1 6 search for the best voting system. One surprising way out, recomme!J.ded by many decision theorists, is that when a CJ) CJ) a: deadlock arises, a "dictator" is chosen by w 113 B B C A �w 3 5 7 lot to break it. Something close to this � r solution actually obtains in certain de mocracies, England for instance, where a constitutional monarch (selected by C A B c 4 9 2 chance in the sense that lineage guaran tees no special biases) has a carefully limited power to break deadlocks under The voting paradox Tournament paradox based on magic square certain extreme conditions.

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© 1974 SCIENTIFIC AMERICAN, INC The voting paradox can arise in any situation in which a decision must be A made between two alternatives from a set of three or more. Suppose that A, B and C are three men who have simul taneously proposed marriage to a girl. The rows of the matrix for the voting paradox can be used to show how she ranks them with respect to whatever three traits she considers most impor tant, say intelligence, physical attrac tiveness and income. Taken by pairs, the poor girl finds that she prefers A to B, B to C and C to A. It is easy to see how similar conflicts can arise with respect to one's choice of a job, where to spend a vacation and so on. Paul R. Halmos once suggested a de lightful interpretation of the matrix. Let A, Band C stand for apple pie, blueber ry pie and cherry pie. A certain restau rant offers only two of them at any given B meal. The rows show how a customer ranks the pies with respect to three prop erties, say taste, freshness and size of slice. It is perfectly rational, says Hal mos, for the customer to prefer apple pie to blueberry, blueberry to cherry and cherry to apple. Experts differ on how often nontransi tive orderings such as this one arise in daily life, but some recent studies in psy chology and economics indicate that they are commoner than one might sup pose. There are even reports of experi ments with rats showing that under cer tain conditions the pairwise choices of individual rats are nontransitive. (See Warren S. McCulloch, "A Heterarchy of Values Determined by the Topology of Nervous Nets," Bulletin of Mathematical Biophysics, Volume 7, 1945, pages 89- �.) C Similar paradoxes arise in round-robin tournaments between teams. Assume that nine tennis players are ranked in ability by the numbers 1 through 9, with the best player given the number 9 and the worst the number 1. The matrix in the illustration at the right on the oppo site page is the familiar order-3 magic square. Let rows A, Band C indicate how the nine players are divided into three teams with each row comprising a team. In round-robin tournaments be tween teams, where each member of one team plays once against each member of the others, assume that the stronger play er always wins. It turns out that team A defeats B,.B defeats C and C defeats A, in each case by five games to four. It is impossible to say which team is the strongest. The same nontransitivity holds if columns D, E and F of the matrix are the teams. Many paradoxes of this type were N ontransitive sucker bet based on magic square: A � B � C � A

12 1 © 1974 SCIENTIFIC AMERICAN, INC jointly investigated by Leo Moser and J. sucker is allowed to draw a card from tives are randomized with equal odds. W. �100n. Some of the Moser-Moon par any set, then you draw a card from a We shall assume that a penny is used. adoxes underlie striking and little-known different set. The high card wins. It is If it is flipped three times, there are sucker bets. For example, let each row easy to prove that no matter what set eight equally probable outcomes: HHH, (or each column) of an order-3 magic the sucker draws from, you can pick a HH� HTH, HTT, THH, THT, TTH square matrix be a set of playing cards, set that gives you winning odds of five to and TTT. One player selects one of these say the ace, six and eight of hearts for four. Set A beats B, B beats C and C triplets and the other player selects a set A, the three, five and seven of spades beats A. The victim may even be allowed different one. The penny is then flipped for set B and the deuce, four and nine to decide each time whether the high or repeatedly until one of the chosen trip of clubs for C [see illustration on pre the low card wins. If you play low card lets appears as a run and wins the game. ceding page]. Each set is randomized wins, simply pick the winning pile with For example, if the chosen triplets are and placed face down on a table. The respect to a non transitive circle that goes HHT and THT and the flips are the other way. A good way to play the THHHT, the last three flips show that game is to use sets of cards from three HHT has won. In brief, the first triplet decks with backs of different colors. The to appear as a run wins. packet of nine cards is shuffled each One is inclined to assume that one time, then separated by the backs into triplet is as likely to appear first as any the three sets. The swindle is, of course, other, but it takes only a moment to isomorphic with the tennis-tournament realize that this is not the case even with paradox. doublets. Consider the doublets HH, Nontransitivity prevails in many other HT, TH and TT. HH and HT are equal simple gambling games. (See this de ly likely to appear first because after the partment for December, 1970, for the first H appears it is just as likely to be description of a set of nontransitive dice.) followed by an H as by a T. The same In some cases, such as the top designed reasoning shows that TT and TH are A�B�C�A by Andrew Lenard [see top illustration equal. Because of symmetry HH = TT at left], the nontransitivity is easy to un and HT = TH. TH beats HH with odds Nontransitive top derstand. The lower part of the top is of three to one, however, and HT beats fixed but the upper disk rotates. Each of TT with the same probability. Consider A B two players chooses a different arrow, HT and TT. TT is always preceded by the top is spun (in either direction) and HT except when TT appears on the first 1 2 2 4 the person whose arrow points to the sec two flips. This happens in the long run tion with the highest number wins. A only once in four times, and so the prob beats B, B beats C and C beats A, in each ability that HT beats TT is 3/4. The bot case with odds of two to one. tom illustration on this page shows the 4 5 6 3 In a set of four bingo cards designed probability that B, the second player, by Donald E. Knuth [see middle illustra will win for all pairs of doublets. tion at left] the nontransitivity is clever C D When we turn to triplets, the situation ly concealed. Two players each select a becomes much more surprising. Since it bingo card. Numbers from 1 through 6 does not matter which side of a coin is 1 3 1 5 are randomly drawnwithout replace designated heads, we know that HHH = ment, as they are in standard bingo. If a TTT, TTH = HHT, HTH = THT and called number is on a card, it is marked so on. When we examine the probabili with a bean. The first player to complete ties for unequal pairs, however, we dis 4 5 2 6 a horizontal row wins. Here, of course, cover that the game is not transitive. 1'\0 the numbers are just symbols; they can matter what triplet the first player takes, A� B�C�D�A be replaced by any set of six different the second player can select a better one. symbols. I leave it to the reader to work The upper illustration on the opposite Nontransitive bingo cards out the probabilities that show card A page gives the probability that B, the beats B, B beats C, C beats D and D second player, defeats A for all possible beats A. The game is transitive with pairings. To find B's best response to a HH HT TH TT � three players, but the winning odds for triplet chosen by A, find A's triplet at the the four possible triplets are surprising. top, go down the column until you reach One of the most incredible of all non a probability shown in color, then move HH 1/2 1/4 1/2 transitive betting situations, discovered left along the row to B's triplet on the (appropriately) by a mathematician left. named Walter Penney, was given as a Note that B's probability of winning HT 1/2 1/2 3/4 problem in the Journal of Recreational is, at the worst, 2/3 (or odds of two to Mathematics (October, 1969, page 241). one) and can go as high as 7/8 (or odds It is not well known, and most mathe of seven to one). The seven-to-one odds TH 3/4 1/2 1/2 maticians simply cannot believe it when are easy to comprehend. Consider THII they firsthear of it. It is certainly one of and IlHH. If HHH first appears any TT 1/2 1/4 1/2 the finest of all sucker bets. It can be where except at the start, it must be pre played with a penny, or as a side bet on ceded by a T, which means that THH the reds and blacks of a roulette wheel, has appeared earlier. HHH wins, there Probabilities 0/ B winning or in any situation in which two alterna- fore, only when it appears on the first

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© 1974 SCIENTIFIC AMERICAN, INC three Hips. Clearly this happens only once in eight Hips. -� HHH HHT HTH HTT THH THT TTH TTT Barry Wolk of the University of Mani toba has discovered a curious rule for determining the best triplet. Let X be the HHH 1/2 2/5 2/5 V8 5/12 3/10 1/2 Hrst triplet chosen. Convert it to a binary number by changing each H to 0 and each T to 1. Divide the number by 2, HHT 1/2 213 213 1/4 5/8 1/2 7/10 round down the quotient to the nearest integer, multiply by 5 and add 4. Ex press the result in binary, then convert HTH 3 113 1/2 1/2 1/2 3 the last three digits back to Hand T. /5 /8 7/12 Nontransitivity holds for all higher n tuplets. A chart supplied by Wolk gives HTT the winning probabilities for B in all pos 3/5 1/3 1/2 1/2 1/2 3/4 7/8 sible pairings of quadruplets [see illus tration on next page]. Like the preced ing two charts and charts for all higher THH 7/8 3/4 1/2 1/2 1/2 113 3/5 n-tuplets, the matrix is symmetric about the center. The upper right quadrant is the lower left quadrant upside down, THT 3 1/2 1/2 1/2 113 3 and the same holds for the upper left and �12 /8 /5 lower right quadrants. The probabilities for B's best responses to A are shown in TTH color. 7/10 1/2 5/8 1/4 213 213 1/2 In studying these figures Wolk dis covered another kind of anomaly as sur prising as nontransitivity. It has to do TTT 1/2 3/10 5/12 V8 2/5 2/5 1/2 with what are called waiting times. The waiting time for an n-tuplet is the aver age number of tosses, in the long run, Probabilities of B winning in a triplet game until the specifiedn-tuplet appears. The longer you wait for a bus, the shorter becomes the expected waiting time. Pen I have no idea why it works. It just at the first letter of the top tuplet and ask nies, however, have no memory, so that cranks out the answer as if by magic, like yourself if the seven letters, beginning the waiting time for an n-tuplet is inde so many of Conway's other algorithms. with this first one, correspond exactly to pendent of all previous Hips. The wait The key to Conway's procedure is the the first seven letters of the tuplet below ing time for Hand T is 2. For doublets calculation of four binary numbers that it. Obviously they do, and so we put a 1 the waiting time is 4 for HT and TH and Conway calls leading numbers. Let A above the first letter. Next look at the 6 for HH and TT. For triplets the wait stand for the 7-tuplet HHTHHHT and second letter of the top tuplet and ask if ing times are 8 for HHT, HTT, THH B for TIlHTHHH. We want to deter the six letters, starting with this one, cor and TTH; 10 for HTH and THT, and 14 mine the probability of B beating A. To respond to the first six letters of the for HIlH and TTT. None of this contra do this write A above A, B above B, A tuplet below. Clearly they do not, and so dicts what we know about which triplet above Band B above A [see illustration we put 0 above the second letter. Do the of a pair is likely to show first. With below]. Above the top tuplet of each five letters starting with the third letter quadruplets, however, contradictions pair a binary number is constructed as of the top tuplet correspond to the first arise with six pairs. For example, THTH follows: Consider the firstpair, AA. Look five letters of the lower tuplet? No, and has a waiting time of 20 and IlTHH a waiting time of 18. Yet TIl TIl is more likely to turn up before HTHH with a probability of 9/14, or well over 1/2. In 1000100=68 0000001= 1 other words, an event that is less fre A= HHTHHHT A= HHTHHHT quent in the long run is likely to happen A= HHTHHHT B= THHTHHH before a more frequent event. There is AA-AB : BB-BA no logical contradiction involved here, but it does show that "average waiting 68-1 : 64-35 time" has peculiar properties. There are many ways to calculate the 67 : 29 probability that one n-tuplet will pre 1000000= 64 0100011= 35 cede another. You can do it by summing B= THHTHHH B= THHTHHH infinite series, by drawing tree diagrams, B= THHTHHH A= HHTHHHT by recursive techniques that produce sets of linear equations and so on. One of the strangest and most efficient techniques was recently devised by John Horton Conway of the University of Cambridge. John Horton Conway's algorithm for calculating odds of B's n-tuplet beating A's n-tuplet

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© 1974 SCIENTIFIC AMERICAN, INC so this letter also gets O. The fourth let course be 1. When compared with a dif a probability of 1 that H beats HT. ter gets another O. When we check the ferent tuplet, the first digit may or may I conclude with a problem by David fifth letter of the top A, we see that HHT not be 1. L. Silverman, who was the first to intro does correspond to the first three letters The odds in favor of B beating A are duce the Penney paradox in the prob of the lower A, and so the fifth letter gets given by the ratio AA - AB : BB - BA. lems department that he edits for the a 1. Letters six and seven each get O. The In this case 68 - 1 : 64 - 35= 67 : 29. Journal of Recreational Mathematics. "A leading A number," or AA, is 1000- As an exercise the reader can try calcu The reader should have little difficulty 100, in which each 1 corresponds to a yes lating the odds in favor of THH beating solving it by Conway's algorithm before answer, each 0 to a no. Translating HHH. The four leading numbers will be the answer appears next month. TTHH 1000100 from binary to decimal gives us AA=7, BB=4, AB=O and BA=3. has a waiting time of 16 and HHH has 68 as the leading number for AA. Plugging these into the formula, AA - a waiting time of 14. Which of these The bottom illustration on the pre AB : BB - BA gives odds of 7 - 0 : tuplets is most likely to appear first and ceding page shows the results of this pro 4 - 3, or 7 : 1, as expected. The algo with what probability? cedure in calculating leading numbers rithm works just as well on triplets of AA, BB, AB and BA. Whenever an n unequal lengths. If the formula is ap The four tangram problems given last tuplet is compared with itself, the first plied, for example, to A =HT and B = month, involving holes that do not : - digit of the leading number must of H, it becomes 3 - 0 1 1 = 3 : 0, or touch one another or the border, are

'>(HHHH HHHT HHTH HHTT HTHH HTHT HTTH HTTT THHH THHT THTH THTT TTHH TTHT TTTH TTTT HHHH 2 2 3 4 3 3 3 V2 /5 /5 /10 5/12 /11 0/11 V16 3/8 /8 /8 V4 /8 7122 V2

HHHT V2 213 213 V2 5/8 4/7 4/7 V8 9/16 9/16 9/16 5/12 9/16 V2 15122

HHTH 3 3 /7 /5 V3 V2 /5 5 V2 V2 5/12 5/12 9/16 9/16 5/14 V2 �16 5/8

HHTT 3 3/7 213 213 3 /5 V3 V2 5/9 5/12 5/12 9/16 9/16 V2 9/14 7/12 /4

HTHH 2 4/7 �1O V2 /5 V2 V2 V2 7/12 7/12 5/14 V2 �16 �16 7/16 5/8

HTHT 3 2/7 4 7/12 /8 /9 V2 V2 V2 7/16 7/16 V2 9/14 7/16 7/16 �16 5/8

HTTH 7/11 3/7 V2 V3 V2 V2 V2 V2 V2 9/16 5/12 7/12 �12 7/16 5/8

HTTT �11 3/7 V2 V3 V2 1/2 V2 V2 V2 9/16 5/12 7/12 7/12 7/8 15/16

THHH 15/16 �8 7/12 �12 5/12 9/16 V2 V2 V2 V2 V2 V3 V2 3/7 7/11

THHT 5/8 7/16 7/12 7/12 5/12 9/16 V2 V2 V2 V2 V2 V3 V2 3/7 7/11

THTH 4 2/7 3 5/8 7/16 7/16 7/16 9/14 V2 7i16 7/16 V2 V2 V2 /9 /8 7/12

THTT 1/2 4/7 2 5/8 7/16 7/16 7/16 V2 5/14 7/12 7/12 V2 V2 /5 V2 7/10

TTHH 213 213 3/7 3 3/4 7/12 9/14 V2 9/16 9/16 5/12 5/12 5/9 V2 V3 /5

TTHT /7 3 5/8 7/16 V2 5/14 9/16 9/16 5/12 5/12 V2 V2 5 3/5 V2 V3 /5

TTTH 15122 1/2 9/16 5/12 9/16 9/16 9/16 V8 4/7 4/7 5/8 V2 213 213 V2

TTTT 1 3 3 4 4 3 2 2 12 7122 3/8 V4 /8 3/8 /8 V16 /11 /11 5/12 /10 /5 /5 V2

Probabilities of B winning in a quadruplet game

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© 1974 SCIENTIFIC AMERICAN, INC solved as shown in the upper illustration at the right. At top left is a way of mak ing two unit square holes. At top right are two holes, one a unit square and the other a triangle of area 1. At bottom left is a way of making a square hole and two triangular holes. (The fit is extremely close. The top triangle's hypotenuse is longer than the length it must span by only .121+.) At bottom right are two rectangular holes and one triangular hole. Ronald C. Read has proved that a tan gram that is snug except for one or more holes cannot have more than one hole if the holes do not touch one another or the border. The smallest possible hole is equal to a small triangular tan. No mat ter how two such holes are placed so that they do not touch, at least 17 triangles are required to isolate them from a tan gram border. Since the seven tans are made of 16 such triangles, completing the required tangram is impossible. For nonsnug tangrams it appears that no more than three holes not touching one another or the border are possible, al though I know of no proof. The square is the only snug tangram with all its sides irrational. This is how Solutions to last month's hole tangrams Read proves it. As I explained last month, an irrational tangram drawn on graph paper with the unit square tan r r oriented orthogonally would have all its edges making 45-degree angles with the matrix lines. All corners clearly must be either 90 degrees or 270 degrees. Since [ each side is a multiple of v'2 and the " total area is 8, it follows that any irra tional snug tangram will be a tetromino composed of four squares, e ach V2 on the side. There are five tetrominoes. One of them, the square, we know can be formed. Each of the other four is easily Impossibility proof for the nonsquare tetrominoes proved impossible by placing the square tan in each of three possible positions [see lower illustration at right] and then than 10. The solution is unique for any formula (x + 1)3 -x3 = y3 has an inte exploring ways of completing the tet set of eight distinct positive integers. gral solution. When this is written x3 + romino. The firsttetromino is ruled out Two readers, J. A. McCallum and Shel y3 = (x + 1)3, we see at once that it is a ' at once because there is no way to place don B. Akers, each asked themselves if case of Fermat's last theorem, with ex the two large triangles. In the other a magic pyramid could be constructed ponents of 3, which was shown long ago three cases, for each position of the with eight consecutive positive integers. to have no integral solution. square tan there are at most only four Each found the only solution and proved In mentioning that the sum of the first ways to place the two large triangles. In it unique. The numbers are 4, 5, 6, 7, 8, n consecutive stars is square only when n every case, after the square and two 9, 10, 11, with a magic constant of 24. is 1 or 169, I got my facts a bit garbled. large triangles are placed there is no spot This was first established in 1973 by for the rhomboid. Thus the square is the uly's article on hex and star numbers John Harris on the basis of 1942 results only possible irrational snug tangram. J asked if a hex could be a cube. David reported by Louis J. Mordell on page Chess, Sin Hitotumatu and Wesley 271 of Diophantine Equations. r. Matrix' magic-pyramid problem in Johnston were the first of many readers Harris and G. J. Westerink each cor D June intrigued many readers. Hiram to point out how easily this can be an rected another error. I said that all Fuller Gutgasz pointed out that the solu swered in the negative. As I showed in square stars begin with 1, but this is not tion is unique in a stronger sense than I the article, every hex is the difference be true. The 12th square star begins with 9, supposed. It is unnecessary to restrict the tween two consecutive cubes, therefore and thereafter the numbers can start labeling to positive numbers no greater the question is the same as asking if the with any positive digit.

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Electrostatic motors are powered by the electric field of the earth

conventional energy resources? Several turns in the horizontal plane on low limitations must first be overcome. For friction bearings. Each spoke of the example, a single sharp point can draw "electric wheel," as Franklin called the electric current from the surrounding air machine, consists of a glass rod with a at a rate of only about a millionth of an brass thimble at its tip. An electrostatic Conducted by C. L. Stong ampere. An antenna consisting of a sin charge for driving the motor was stored gle point at the top of a 60-foot wire in Leyden jars. A Leyden jar is a primi could be expected to deliver about a mi tive form of the modern high-voltage A lthough no one can make a perpet croampere at 2,000 volts; the rate is capacitor. Franklin charged his jars with fi ual motion machine, anyone can eqaivalent to .002 watt. A point-studded an electrostatic generator. tap the earth's electric field to run balloon tethered by a wire at an altitude The high-voltage terminals of two or a homemade motor perpetually. The of 75 meters might be expected to deliv more Leyden jars that carried charges field exists in the atmosphere between er .075 watt. A serious limitation appears of opposite polarity were positioned to the earth's surface and the ionosphere as as the altitude of the antenna exceeds graze the thimbles on opposite sides of an electric potential of about 360,000 about 200 meters. The correspondingly the rotating wheel. The motor was start volts. Estimates of the stored energy higher voltages become difficult to con ed by hand. Thereafter a spark would range from a million kilowatts to a bil fine. jump from the high-voltage terminal to lion kilowatts. At an altitude of 200 meters the an each passing thimble and impart to it a Energy in this form cannot be drawn tenna should pick up some 20,000 volts. charge of the same polarity as that of the on directly for driving ordinary electric Air conducts reasonably well at that po terminal. The force of repulsion between motors. Such motors develop mechanical tential. Although nature provides effec the like charges imparted momentum to force through the interaction of mag tive magnetic materials in substances the wheel. netic fieldsthat are generated with high such as iron, nickel and cobalt, which ex Conversely, the thimbles were attract electric current at low voltage, as Mi plains why the electric-power industry ed by the oppositely charged electrode chael Faraday demonstrated in 182l. developed around Faraday's magnetic of the Leyden jar Franklin placed on the The earth's field provides relatively low dynamo, no comparably effectiveinsulat opposite side of the wheel. As the thim direct current at high voltage, which is ing substances exist for isolating the high bles grazed that jar, a spark would again ideal for operating electrostatic motors voltages that would be required for elec transfer charge, which was of opposite similar in principle to the machine in trostatic machines of comparable power. polarity. Thus the thimbles were simul vented by Benjamin Franklin in 1748. Even so, electrostatic motors, which are taneously pushed and pulled by the Motors of this type are based on the far simpler to build than electromagnetic high-voltage terminals exactly as was force of mutual attraction between un ones, may find applications in special en needed to accelerate the wheel. like electric charges and the mutual re vironments such as those from which Franklin was not altogether happy pulsion of like charges. The energy of magnetism must be excluded or in pro with his motor. The reason was that run the field can be tapped with a simple viding low power to apparatus at re ning it required, in his words, "a foreign antenna in the form of a vertical wire mote, unmanned stations by tapping the force, to wit, that of the bottles." He that carries one sharp point or more at earth's field. made a second version of the machine its upper end. During fair weather the Apart from possible applications elec without Leyden jars. antenna will pick up potential at the rate trostatic motors make fascinating play In this design the rotor consisted prin of about 100 volts for each meter of things. They have been studied exten cipally of a 17 -inch disk of glass mount height between the points and the earth's sively in recent years by Oleg D. Jefi ed to rotate in the horizontal plane on surface up to a few hundred feet. At menko and his graduate students at West low-friction bearings. Both surfaces of higher altitudes the rate decreases. Dur Virginia University. The group has re the disk were coated with a film of gold, ing local thunderstorms the pickup can constructed models of Franklin's motors except for a boundary around the edge. amount to thousands of volts per foot. A and developed advanced electrostatic The rotor was thus constructed much meteorological hypothesis is that the machines of other types. like a modern flat-plate capacitor. field is maintained largely by thunder Although Franklin left no drawing of Twelve evenly spaced metal spheres, storms, which pump electrons out of his motor, his description of it in a letter cemented to the edge of the disk, were the air and inject them into the earth to Peter Collinson, a Fellow of the Royal connected alternately to the top and through bolts of lightning that continu Society, enabled Jefimenko to recon bottom gold films. Twelve stationary ously strike the surface at an average rate struct a workingmodel [see illustration thimbles supported by insulating col of 200 strokes per second. on opposite page]. Essentially the ma umns were spaced around the disk to Why not tap the field to supplement chine consists of a rimless wheel that graze the rotating metal spheres. 'When

126 © 1974 SCIENTIFIC AMERICAN, INC Franklin placed opposite charges on the creased by adding both moving and fixed crosses of ebonite. Each insulating arm top and bottom films and gave the rotor electrodes. This stratagem is limited by of the crosses supported a comblike row a push, the machine ran just as well as the available space. If the electrodes are of sharp needle points that grazed the his first design, and for the same reason. spaced too close, sparks tend to jump glass. According to Franklin, this machine from electrode to electrode around the When opposing combs on opposite would make up to 50 turns a minute and rotor, thereby in effect short-circuiting sides of the glass were charged in oppo would run for 30 minutes on a single the machine. Alternatively the rotor site polarity to potentials in excess of charge. could be made cylindrical to carry elec 2,000 volts, air in the vicinity of the Jefimenko gives both motors an initial trodes in the form of long strips or plates. points on both sides of the glass was charge from a 20,000-volt generator. This scheme could perhaps increase the ionized. A bluish glow surrounded the They consume current at the rate of output power by a factor of 1,000. points, which emitted a faint hissing about a millionth of an ampere when Reviewing the history of electrostatic sound. The effect, which is variously they are running at full speed. The rate machines, Jefimenko came across a paper known as St. Elmo's fire and corona dis is equivalent to .02 watt, which is the published in 1870 by Johann Christoff charge, deposited static charges on both power required to lift a 20-gram weight Poggendorff, a German physicist. It de sides of the rotor. 10 centimeters (or an ounce 2.9 inches) scribed an electrostatic motor fitted with Almost the entire surface of the glass in one second. a rotor that carried no electrodes. The acquired a coating of either positive or Jefimenko wondered if Franklin's mo machine consisted of an uncoated disk of negative fixed charges, depending on the tor could be made more powerful. As glass that rotated in the vertical plane on polarity of the combs. The forces of re Jefimenko explains, the force can be in- low-friction bearings between opposing pulsion and attraction between glass so

DY'ASS thimbles

LCldCYIjar

Benjamin Franklin's electrostatic motor

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© 1974 SCIENTIFIC AMERICAN, INC one cannot achieve so much as with one el ectrodCS hundred pounds." Electrostatic motors are now classified in general by the method by which charge is either stored in the machine or transferred to the rotor. PoggendorH's machine belongs to the corona type, which has attracted the most attention in recent years. Although its measured efficiency is better than 50 percent, Pog gendorH regarded it merely as an appa ratus for investigating electrical phe nomena. He wrote that "it would be a sanguine hope if one wanted to believe that any useful mechanical eHect could be achieved with it." PoggendorH's negative attitude to ward the usefulness of his design may well have retarded its subsequent de velopment. A modem version of the ma chine constructed in Jefimenko's labora tory has an output of approximately .1 horsepower. It operates at speeds of up to 12,000 revolutions per minute at an efficiency of substantially more than 50 percent. In one form the modern corona motor consists of a plastic cylinder that Oleg D.lefimenko'scorona motor turns on an axial shaft inside a concentric set of knife-edge electrodes that spray charge on the surface of the cylinder [see charged and the combs were substantial ing and unidirectional. When the teeth top illustration on this page]. Forces that ly larger than they were inFranklin's were perpendicular to the glass surface, act between the sprayed charges and the charged thimbles. The forces were also the forces were symmetrical, as they knife-edge electrodes impart momentum steadier, because in eHect the distances were in Franklin's motor. When the ma to the cylinder. between the combs and the charged chine was started by hand, it ran equally Machines of this kind can be made of areas remained constant. It should be well in either direction. almost any inexpensive dielectric mate noted that adjacent combs on the same PoggendorH was immensely pleased rials, including plastics, wood and even side of the glass carried charges of oppo by the rate at which his machine con cardboard. The only essential metal site polarity, so that the resulting forces verted charge into mechanical motion. parts are the electrodes and their inter of attraction and repulsion acted in uni He concluded his paper with a faintly connecting leads. Even they can be con son to impart momentum to the disk, as odious reference to Franklin's device. trived of metallic foil backed by any stiH they did in Franklin's motor. "That such a quantity of electricity must dielectric. The shaft can be made of By continued experimentation Pog produce a far greater force than that in plastic that turns in air bearings. By re gendorH learned that he should slant the the [Franklin] electric roasting spit," he sorting to such stratagems experimenters teeth of the combs to spray charge on the wrote, "is perfectly obvious and nowa can devise motors that are extremely glass at an angle. The resulting asym days would not be denied by Franklin light in proportion to their power output. metrical force made the motor self-start- himself. With one grain of gunpowder Corona motors require no brushes or commutators. A potential of at least 2,000 volts, however, is essential for ini tiating corona discharge at the knife edges. A smaller and simpler version of the machine was demonstrated in 1961 by J. D. N. Van Wyck and G. J. Kuhn in South Africa. This motor consisted of a plastic disk about three millimeters thick and 40 millimeters in diameter support ed in the horizontal plane by a slender shaft that turned in jeweled bearings. Six radially directed needle points grazed the rim of the disk at equal intervals. When the machine operated from a source of from 8,000 to 13,000 volts, ro tational speeds of up to 12,000 revolu Conventional electrodes (left) and improved electrodes (right) tions per minute were measured.

I made a corona motor with Plexiglas bly. The rotor must be balanced both nected to a 20-foot length of metallic tubing two inches in diameter and one statically and dynamically. tinsel of the kind that serves for decorat and a half inches long. It employed stiff Static balance was achieved by experi ing a Christmas tree. The tinsel func backed single-edge razor blades as elec mentally adding small bits of adhesive tioned as multiple needle points. Strips trodes. The bore of the tube was lined tape to the inner surface of the alumi cut from window screening would with a strip of aluminum foil, a strata num foil that lines the cylinder until the doubtless work equally well. gem devised in Jefimenko's laboratory to rotor remained stationary at all positions The upper end of the tinsel was hoist increase the voltage gradient in the vi to which it was set by hand. When the ed aloft by a cluster of three weather cinity of the electrodes and thus to in rotor was balanced and power was ap balloons. Such balloons, each three feet crease the amount of charge that can be plied, the motor immediately came up to in diameter, and the helium to inHate deposited on the surface of the cylinder. speed, but it shook violently. I had cor them are available from the Edmund I coated all surfaces of the razor blades rected the imbalance caused by a lump Scientific Co. (300 Edscorp Building, except the cutting edges and all inter of cement at one end of the rotor by add Barrington, N.J. 08007). The weight in connecting wiring with "anticorona ing a counterweight on the opposite side pounds that a helium-filled balloon of dope," a cementlike liquid that dries to at the opposite end of the cylinder. Cen spherical shape can lift is roughly equal form a dielectric substance that reduces trifugal forces at the ends were 180 de to a quarter of the cube of its radius in the loss of energy through corona dis grees out of phase, thus constituting a feet. To my delight the motor began to charges in nonproductive portions of the couple. run slowly when the tinsel reached an circuit. The dynamic balancing, which is altitude of about 100 feet. At 300 feet The axial shaft that supports the cylin achieved largely by cut-and-try methods, the rotor made between 500 and 700 der on pivot bearings was cut out of a took about as much time as the remain revolutions per minute. steel knitting needle. The ends of the der of the construction. To check for A note of warning is appropriate at shaft were ground and polished to 30- dynamic balance suspend the motor free this point. Although a 300-foot vertical degree points. To form the points I ly with a string, run it at low speed and antenna can be handled safely in fair chucked the shaft in an electric hand judge by the wiggle where a counter weather, it can pick up a lethal charge drill, ground the metal against an oil weight must be added. Adhesive tape during thunderstorms. Franklin was in stone and polished the resulting pivots makes a convenient counterweight ma credibly lucky to have survived his cele against a wood lap coated with tripoli. terial because it can be both applied and brated kite experiment. A European in The bearings that supported the piv shifted easily. vestigator who tried to duplicate Frank ots were salvaged from the escapement I made the motor as light and friction lin's observations was killed by a bolt of mechanism of a discarded alarm clock. A less as possible with the objective of op lightning. The 300-foot antenna wire can pair of indented setscrews could be sub erating it with energy from the earth's hold enough charge to give a substantial stituted for the clock bearings. The sup field. The field was tapped with an an jolt, even during fair weather. Always porting frame was made of quarter-inch tenna consisting of 300 feet of No. 28 ground the lower end of the wire when Lucite. The motor can be made self gauge stranded wire insulated with plas it is not supplying a load, such as the starting and unidirectional by slanting tic. It is the kind of wire normally em motor. the knife-edges. Those who build the ployed for interconnecting electronic To run the motor connect the antenna machine may discover, as I did, that the components and is available from deal to one set of electrodes and ground the most difficult part of the project, balanc ers in radio supplies. other set. Do not connect the antenna to ing the rotor, is encountered after ass em- The upper end of the wire was con- an insulated object of substantial size,

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© 1974 SCIENTIFIC AMERICAN, INC such as an automobile. A hazardous charge can accumulate. Never fly the balloon in a city or in any other location where the antenna can drift into contact with a high-voltage power line. Never fly it below clouds or leave it aloft unat tended. A variety of corona motors have been constructed in Jefimenko'slaboratory. He has learned that their performance can be vastly improved by properly shaping the corona-producing electrodes [see bottom illustration on page 128]. The working surface of the rotors should be made of a fairly thin plastic, such as Plexiglas or Mylar. l\loreover, as I have mentioned, the inner surface of the cylin der should be backed by conducting foil to enhance the corona. Effective cyl inders can be formed inexpensively out of plastic sewer pipe. Corona rotors can of course also be made in the form of electret disks. One model consists of a series of disks mounted on a common shaft. Double edged electrodes placed radially be tween adjacent disks function much like Poggendorff's combs. This design needs no foil lining or backing because a poten Circuit arrangement for the slot.effect electret motor tial gradient exists between electrodes on opposite sides of the disks. It is even possible to build a linear corona motor, a design that serves to achieve translation al motion. A strip of plastic is placed be tween sets of knife-edge electrodes slant ed to initiate motion in the desired direc tion. Notwithstanding the problem of han dling potentials on the order of a million volts without effective insulation mate rials, Jefimenko foresees the possibility of at least limited application of corona power machines. In The Physics Teacher (March, 1971) he and David K. Walker wrote: "These motors could be very use ful for direct operation from high-volt age d.c. transmission lines as, for exam ple, the 800 kV Pacific Northwest-South west Intertie, which .is now being con structed between the Columbia River basin and California. It is conceivable that such motors could replace the com plex installations now needed for con verting the high-voltage d.c. to low voltage a.c. All that would be required if corona motors were used for this pur pose would be to operate local low-volt age a.c. generators from corona motors powered directly from the high-voltage d.c. line." As Jefimenko points out, a limiting factor of the corona motor is its required minimum potential of 2,000 volts. This limitation is circumvented by a novel electrostatic motor invented in 1961 by lefimenko's slot·effectelectret motor a Russian physicist, A. N. Gubkin. The

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Indonesia will unite its 5,000 islands with a synchronous communications satellite system --first in the Eastern Hemisphere --which will provide nationwide tele vision for education and entertainment and island-to-island telephone service for most of its 120 million people. Mountains, jungles, and vast stretches of ocean have made it difficult to link existing telecommunications with conventional micro wave relays and submarine cables. Lack of communications in remote locations has hindered development of many mineral-rich areas of the 3,000-mile archipelago.

Work is now under way at Hughes to define the Indonesia system, which includes two satellites and 50 earth stations. The satellites are similar to those now in ser vice for Telesat Canada and Western Union, which were also built by Hughes. Opera tions are scheduled to begin in mid-1976.

A mobile dockside trainer for U.S. Navy ship combat teams is now being built by Hughes under a recently awarded contract. Called MISTER (for MobileIntegrated System Trainer, Evaluator, and Recorder), it will allow the Navy to prepare and execute simulated fleet exercises by simultaneously presenting realistic tactical problems to the combat te,ams of two ships and to evaluate their performance . Up to five MISTERS can be tied into one exercise to provide coordinated task-force level training. Because the exercises are controlled by minicomputers, the combat teams train at actual battle stations without need for ship deployment or electro magnetic radiation, which results in a significant reduction in fuel and other operating costs.

The Hellfire (Helicopter-Launched Fire and Forget) missile, which Hughes is now de veloping under contract to the U.S. Army Missile Command, is an advanced modular missile for use against tanks, vehicles, and ground emplacements. The next-genera tion missile beyond the Army's present TOW, Hellfire has a greater range and can use four different seeker-heads --laser, radar frequency-infrared, optical con trast, or imaging infrared --which give it an all-weather, day-night capability. Hughes has one year to build a prototype missile, launcher, functional cockpit mock up, and other equipment for a competitive evaluation.

Systems Engineers and Analysts: Our Field Service and Support Division has per sonnel requirements for design and developmental work on the MISTER program for: logic design engineers (BS or MSin EE or Physics, digital design experience); system engineers (BSEE or Physics, training simulator experience); real-time pro grammer/analysts (technical degree, real-time simulation experience). U.S. citi zenship required. Please send your resume to: D.I. Wingate, Hughes Aircraft Com pany, P.O. Box 90515, Los Angeles, CA 90009. An equal opportunity M/F employer.

X-ray lithography for batch production of microelectronic devices has been brought closer to practical application by Hughes research scientists. Their technique involves exposing X-ray sensitive polymeric resists through a high-resolution mask generated by scanning electron-beam systems. Advantages of X-ray lithography in clude large-area parallel exposure, 0.2-micron resolution, off-contact exposure, insensitivity to dust and contamination, use of positive or negative resists, uni form exposure with depth, and no requirement to place mask or substrate in a vacuum.

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132

© 1974 SCIENTIFIC AMERICAN, INC motor is based on an electret made in wiching the electret alternately between 1922 by Mototaro Eguchi, professor of pairs of metal plates, Jefimenko employs «It� physics at the Higher Naval College in opposing pairs of adjacent plates [see il Tokyo. lustration on page 129). The adjacent is the best arm An electret is a sheet or slab of waxy plates are separated by a narrow slot. t offered dielectric material that supports an elec When adjacent plates carry charges of � as tric field, much as a permanent magnet opposite polarity, the electret experi an integral part carries a magnetic field. Strongly ences a force at right angles to the slot charged carnauba-wax electrets are and in the plane of the electret. The ofa n automatic available commercially, along with other strength of the force is at a maximum electrostatic devices, from the Electr"!t because the electret is elose to the elec player." Scientific Company (P.O. Box 4132, Star trodes. Simultaneously the electrodes -High FidelityMagazine City, W.Va. 26505). A recipe for an ef function as shields to prevent the neu fective electret material is 45 percent tralization of the electret by free ions. There are only three carnauba wax, 45 percent water-white Motors based on the slot effect can be automatic turntables in rosin and 10 percent white beeswax. designed in a number of forms. One de the world that have a Some experimenters substitu te Halowax sign consists of an electret in the shape tonearm without for the rosin. of a wafer-thin sheet of Mylar supported tracking error. The ingredients are melted and left by a flat disk of balsa wood 100 milli All three are made by Garrard. to cool to the solid phase in a .direct meters in diameter and three millimeters The unique current electric field of several thousand thick. (A long-lasting charge is imparted Zero Tracking Error volts. The wax continues to support the to the Mylar by immersing it in a field of Tonearm featured by field even though the externalsource of a few thousand volts from an electro these turntables has a potential is turned off [see "The Ama static generator after the motor is as hinged head that keeps teur Scientist," SCIENTIFIC AMElUCAN, sembled.) This rotor is sandwiched be correcting its align Novcmber, 1960, and July, 1968). The tween four semicircular sectors that are ment to the groove as it travels across the electret reacts to neighboring charges cross-connected [see top illustration all cxactly as though it were a charged elec page 130). , record. This is a signifi trode, that is, it is physically attracted or The electret is mounted on a four cant improvement over rcpelled depending on the polarity of the millimeter shaft of plastic that turns in the conventional fixed neighboring electrode. jeweled bearings. The conducting sur head tonearm, which Gubkin harnessed this effectto make faces of the commutator consist of dried has tracking error built a motor. The rotor consisted of a pair of India ink. The brushes are one-millime into it. electrets in the shape of sectors support ter strips of kitchen aluminum foil. The The resultis a cd at opposite ends of a shaft. The center motor operates on a few microwatts of small but irreducible of the shaft was supported transversely power. amount of distortion. by an axle. "Vhen the rotor turned, the Jefimenko has demonstrated a similar Can you hear the difference between electrets were swept between adjacent motor that was designed to turn at a rate the two systems? pairs of charged metallic plates, which of about 60 revolutions per minute and Yes, said the were also in the form of sectors. develop a millionth of a horsepower on "Acoustics" column The plates were electrified by an ex a 24-foot antenna having a small poloni of Rolling Stone magazine. ternal source of power through the polar um probe at its upper end. (By emitting It reported that the Garrard ity-reversing switch known as a commu positive charges probes of this type tap turntable equipped with tator. The commutator applied to the the earth's field somewhat more efficient the Zero Tracking Error electrodes a charge of polarity opposite ly than needle points do.) The perform Tonearm "sounded markedly to the charge of the attracted electret. As ance of the motor easily met the design 'crisper'than other turntables"under otherwise identical test conditions. the electret moved between the attract specifications. The charm of these motors Ask your dealer about the top-of-the ing plates, however, the commutator lies in the fact that, although they do not line Garrard Zero lOOc($209.95) and the switched the plates to matching polarity. accomplish very much, they can run for other zero-tracking-error models. The alternate push and pull imparted cver. It's absurd to tolerate a problem that momentum to the rotor in exact analogy somebody has: � to Franklin's motor. pau; R. BUl :nett (2401 32nd Stree:, alreadYSOlv � � Gubkin's motor was deficient in two S.E., Washmgton, D.C. 200.0 ,) ) suo- major respects. The distances betwcen gests a simple procedure to extract nitro ; the electrodes and the electrets were gen from air for use in the laser de To get your free copy of the new 16-page full-color Garrard Guide, write Garrard, Dept. SA ..lO. needlessly large, so that the forces of at scribed in this department in June. Sim 100 Commercial Street, Plainview, N.Y. 11803. traction and repulsion were needlessly ply burn natural gas, propane or even weak. Moreover, during the electret's alcohol and let the aspirator of the laser transit between electrodes its surfaces pull the combustion products succes were unshielded. Unshielded electrets sively through a bed of lime and a bed attract neutralizing ions from the air and of anhydrous calcium sulfate respective lose their charge within hours or days. ly. Nitrogen of adequate purity will be Both inherent deficiencies of Gubkin's drawn into the laser. A cold trap chilled motor have been corrected in Jefimenko's with dry ice and acetone or any other laboratory by taking advantage of what desiccant can be substituted for the cal is termed the slot effect. Instead of sand- cium sulfate.

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The background light of the night sky and the architecture of the pyram>ids

the planets and illuminated by the sun. astronaut sees it as a luminous arc on The frontispiece shows the oval patch of the curved limb of the earth; he looks by Philip Morrison the zodiacal light seen from the vantage through the region of its origin edgewise, of the Hawaiian crater edge. The stuffof so that it is effectively30 times thicker HE the zodiacal cloud is as ever changing as than it is when it is viewed at the zenith LIGHT OF THE NIGHT SKY , by a river; it is steadily lost to space and from the ground. The main source of en TF. E. Roach and Janet L. Gordon. the sun and is resupplied in a cycle of ergy for this glow (there are several com D. Reidel Publishing Company 100,000 years, probably from the loss of ponents) is the night-long chemical reac ($16.50). "As Earth rotates within the mass by comets and the grinding colli tion among the sunlight-excited atoms of sunlight sheath" blue day gives way to sions of asteroidal material. The cloud is the thin air some 90 kilometers up. Most the sunset drama until at last the stars much denser than its gossamer kin, the of its photons are infrared: vibratory come out. The darkening sky is still blue interstellar dust; ifthe interstellar ma emissions of the hydroxyl radical, prob to the camera, although not to the eye, terial were as dense as the solar, the ably excited by the reaction of atomic even in mid-twilight; the sun's rays are stars of Orion would be invisible. hydrogen with ozone. If this reaction still scattered by the particles in the high The stars are the next component. were capable of emitting green photons air, but those particles are so sparse that They have been sampled ever since Wil with fair efficiency, it would cause a fair the skylight intensity has fallen far below liam Herschel counted offto his devoted ly bright permanent aurora and deep the color threshold of the eye. At the sister Caroline the stars drifting into his sky optical astronomy could hardly exist. official end of twilight the nearest rays eyepiece. (His data compare well with The Milky Way contributes another of the sun illuminate the zenith 200 miles modern numbers to his limit of about the diffuse light, a pedestal on the graph above the ground; sometimes a satellite 14th magnitude.) By extrapolation and above which the individual star spikes up there is caught for a while in the sampling we can reckon that the sphere stand like a grove of bamboo. That is a beam. In the absence of the moon and of stars (mostly in the Milky Way) equals sign of galactic dust. An entire chapter clouds the night sky is 400,000 times in visible light about 100 stars as bright of the book discusses the distribution of fainter than the sky at sunset. But even as Sirius. matter by size in our galaxy, from gas the midnight sky is not truly dark; that Our location in space is fortunate in atoms, dust, pebbles, boulders, r ocks, can easily be proved by looking at a many ways. If we lived in a globular comets, moons and asteroids, rocky and part of the sky where no stars appear to cluster, the sky would dazzle us with gassy planets to stars, dwarf and giant. the unaided vision and then holding a bright stars. With any luck the Sirius of Between the dust and the stars all we black card up to it. that sky would blaze out nearly 10 times have is a tiny local sample and a pench Photons rain down on us detectably as bright as our Venus and would be ant for smooth interpolation.This simple from the entire universe. This little text easily visible by day, but the galaxy and unreliable model predicts the exis book-varied, personal and comprehen would be overwhelmed, and perhaps we tence of five faint stars closer to us than sive-tells where they come from and would not yet have learned of other gal Alpha Centauri, and a large number of how we know. Photometry by eye, cam axies. (Of course, radio intercommunica major and minor planets! era and digitized photomultiplier, sta tion on a few months' round-trip time It is striking that all the main sources tions in orbit, in the oasis of Tamenrasset basis might be possible; "the local of sky light (apart from the light of cities and two miles above the sea on a Hawai SPACE organizations" would be busy and the moon) are of the same order of ian crater (where the authors work) and planning interstellar travel.) magnitude in brightness. There is one star counts by William Herschel and by The bright, colorful polar aurora, ex grand exception. The still unclaimed Bart Bok and his Harvard "star-counting cited in the upper air by fast particles prize of those who gauge the glow of the brigade" are discussed, with sciences energized by streams from the sun, dis night sky is the real cosmic light: the su from free-radical chemistry to cosmol tinctly masks faint stars whenever it oc perimposed emission of the distant gal ogy, at a level that requires some pre curs. Fortunately for astronomers it is axies. They spread out in all directions, vious knowledge but little mathematics. sporadic and zonal; the treatment here until we are looking so far out that the Results are graphically displayed (there is brief. There is, however, the ubiqui passage of light takes us back to the time are 70 figures)and the scientific litera tous night glow. It is dynamic and shift before the galaxies and their stars were ture is widely cited. ing, but it is worldwide and not sporadic. born out of cosmic hydrogen. An upper Five different components of the It is not as bright as the aurora; it is limit can be set at some 5 percent of the night-sky light are assessed, a paradigm striking only to instruments. That is be total sky light. Plausible cosmological of successive approximation. Brightest cause it shines mainly in the deep red, estimates put the expected value rather of all shines the fine dust of our solar where our eyes are only a tenth as sensi lower: about 1 percent. Already we have system, spread out in the orbital plane of tive as they are in the auroral green. The moved our stations out to cislunar space,

135 © 1974 SCIENTIFIC AMERICAN, INC well beyond the aurora and the night Plant a THINK TANK anywhere books, which has color plates and a cou and watch the minds grow! glow. It is not much use to think of mov ple of valuable air views to augment home-office-scnool-park-club-churches-Iaboratory ing among the stars, unless we can hope more conventional photographs and to leave the galaxy, reducing all star draWings, is the novel work of an ama light to a mere patch. Our most plausible teur Egyptologist. He is no amateur at expedition, then, is one to the outer plan science but a well-known low-tempera ets; there the zodiacal light is much ture physicist of Berlin and Oxford, lIe fainter. A large telescope looking toward too has watchfully climbed his pyramids; the galactic pole from such precincts is he presents here a persuasive and novel our best hope for a clear view of the cos set of physicist's inferences from study of Unique instructional games designed by uni mic light. The radio observers may do those man-made hills. versity professors to make learning fun through brain-ta-brain action. Beginning games better here on the earth, but let the visi The essential background of the new can be mastered by youngchildre� final games ble observers dream of an instrument in arguments is as follows. The rulers of will challenge inteiligent adults. These are orbit around Jupiter or its satellite Gany the famous GAMES FOR THINKERS from Egypt built pyramids off and on for two WFF 'N PROOF Publishers. mede: "Put down this book and take ... millenniums. Just five of them dwarf the a cursory glance at the night sky-on a WFF 'N PROOF (logic) 9.75- rest in volume. (The others "were well QUERIES 'N THEORIES (science) 9.75- clear night, you can see forever! " within the ordinary budget," Mendels EQUATIONS (mathematics) 6.50- The book is an outstanding interme sohn drily remarks.) The first of all was ON-SETS (set theory) 6.50- PROPAGANDA (social studies) 7.50- diate text, as refreshing and as wide as the Step Pyramid, built under Zoser. ON-WORDS (word structures) 6.50- the night sky and certainly worth its cost Then came the pyramid at Meidum and CONFIGURATIONS (geometry) 6.50- of 13 cents a page. Its two-page biog TRI-NIM (problem solving) 5.50- the two at Dahshur, all finished under REAL NUMBERS (arithmetic) 2.25- raphies and informal air are winning ad Snefru. Snefru's son Khufu built the WFF (beginner's logic) 2.25- ditions, although one misses two or three Great Pyramid at Giza, 15 miles south of QWIK-SANE (puzzle) 2.25- TAC-TICKLE (pure strategy) 1.25- pages about the instrumentation these Dahshur. The architects of Giza had reachers Manual 1.25- artist-experts use, been apprentices at Dahshur and the TH INKERS Bookends 16.00- 12-Kit THINK TANK & Teachers Manual grand style was continued under Khufu's PYRAMIDS, With THINKERS Bookends (save $9.25) 74.50- HE by Ahmed Fakhry. son and heir, but there it stopped. Few Without THINKERS Bookends(sove$3.25) 64.50- TThe University of Chicago Press later works have as much as a tenth the postage & handling included in above prices ($3.25). THE fuDDLE OF THE PYRAMIDS, bulk of these five, built within two cen Order from: WFF 'N PROOF by Kurt Mendelssohn. Praeger Publish turies, and mainly in the 100 years cen 1490-TW South Boulevard. Ann Arbor. Mi. 48104 ers ($12,95). Professor Fakhry's book is tered on 2600 B.C., the pyramid age. Gifts that are a COMPLIMENT to receive! a small paperback, yet it is careful and The central clue is at Meidum, where comprehensive and imparts the pride the pyramid "looks like a colossal tower and enthusiasm of a man who lived and standing at the edge of a hill. " It has no worked for decades at the pyramids; his smooth sloping walls but three great desert dwelling was almost literally with steps surmounting a conical mound of in their shadows. It is an admirable sum rubble. The rubble has always been mary, replete with dates, diagrams, maps thought to be the work of stone robbers, and many photographs, ·One remarkable but it is far too bulky. No city is near chapter treats the Sphinx, "the great to have used up so much stone. Although man-headed lion" the Egyptians still re robbers have nibbled at the pile, that hill gard as "a source of endless wisdom and of broken debris is the ruin of a pyramid. hope for the future," The builders of the Like the mine tip at Aberfan in Wales, Second Pyramid at Giza excavated pyra the pyramid of Meidum suddenly col mid stone from a quarry where the lapsed while it was still unfinished and Sphinx now stands. Then the Sphinx was poured the bulk of its mantle laterally carved out of a great core of softer rock outward into a roughly circular heap of that had been left behind as unusable. broken limestone. Rather than simply haul away the un A more detailed analysis of the con sightly mass whose natural form may Our 22nd year of service to the World's struction shows how it happened. A pyr have suggested a crouching beast, the amid of ideal blocks bears its load stably, finest craftsmen and technicians. architects and their workmen brilliantly with each vertical column held firmly "'- National Camera transmuted the "eyesore into a sublime on its base. The compressive load is some ...... I 2000 West Union Awe. Dept.JAC ""'" f"9'ewcofl, Colorado, Bono monument." Ever since that time, over 25 atmospheres: high, but not high .. ------... the entire ebb and flow of Egyptian his enough to cause the failure of good I Send a FREE copy of the Ne Flasher I tory, it has been sand-buried and recov stone. Irregular blocks, however, such as ered, embellished, vandalized or cele 1 those we see through a hole into the 1------name brated. Meidum pyramid, touch at only a few I�------I Fakhry, who died last year, was a pro points of contact. The loading is heavy, address 1 I fessional of the most devoted kind, full and the material flees it by thrusting out city of learning and yet resilient enough to ward. One day, perhaps after a lubricat I I welcome the bold proposal to radiograph ing rainstorm like Aberfan's, the growing I state zip I the Second Pyramid of Giza with cosmic outer mantle flowed catastrophically out "'- National Camera ray muons. (No internal tomb is hidden and down, , I 2000 w• ., Un;_" ""e. Dept. JAC � E"91ewoed, C.'oro".,.O"O there, the spark chambers say, too re So much is structural inference. The cently for this book.) The second of these next pyramid, however, is unique; it is

136

© 1974 SCIENTIFIC AMERICAN, INC I·he Bent Pyramid, so named because at FOR GREATER RELAXATION, CONCENTRATION, one level its slope sharply decreases from 54 degrees (about like Meidum) to 43 ... listento your degrees. The story unfolds: This change was made not to save stone (the next pyramid was built entirely at the shal Alpha and Theta brainwaves! lower angle) but to forestall another col Do it with an amazing biofeedback monitor. lapse. A detailed study of the inner struc This ultra-sensitive sensor detects brain sig nals, lets you monitor ( hear and see!) your ture and workmanship of the two pyra Alpha and Theta brainwaves. Great aid to re mids supports the case strongly. The laxation, concentration. This portable (8 x 3 pyramids at Dahshur fit a logical account x 4") lightweight (24 oz.) metal unit has a at last, and the boldness and skill of the unique electrode headband to slip on or off in builders of the steep Great Pyramid seconds without messy creams or solutions. Hooked to amplifier, it filters brainwaves, and emerge even more strongly. (Its masonry signals an audible beep for each Alpha or is remarkably well dressed, although at Theta wave passed. You 'get both audio and great cost in labor.) visual (LE.D.) feedback with this reliable, com The argument continues. For the pletely safe unit. It operates on two 9v tran builders at Dahshur to have bent their sistor batteries, offers features comparable to many costlier models. A comprehensive in- pyramid for safety, they must have been struction booklet is included. partway along, working on a course some YOU MUST Order No. 1635 S JUST $13450Ppd. 50 meters above the ground before the BE DELIGHTEDI LOW COST "STARTER UNIT" EVERYTHING lD ND SElLS HAS A Order No. Ppd. mantle of Meidum was complete. The MUA 71,8095 ...... $55.00 pyramid-building schedules overlapped. ��i��: itM�r;:� ;�n,;U:e��;!�: 'MMij.'i'4IiIIWil'IIIi4H1llu¥ Snefru must have built pyramids all his EDMUND SCIENTIFIC CO. ---, life, and so his son must have done. No I:!��j,gj��gji�m�ligji�iJ �!li;;�'ir300 Edscorp Bldg., Barrington, N.J. 08007 I Send me: __ Biofeedback Trainer(s) king, however great, needs three tombs; No. 1635 Sea. @$134.50; No. 71, 809 Sea. @$55.00 I GIANT FREE CATALOG! Handling, ea. .50 the pyramids were not built solel y as I NEW! 164 PAGES-OVER 4500 UNUSUAL Encl is 0 check 0 M.O. In amount of $ --I ( ) Send FREE 164 Page catalog" S " tombs, although they served as tombs. BARGAINS FOR HOBBYISTS, SCHOOLS, I Their great centrally directed work force INOUSTRY ... JUST CHECK COUPON! Name I could not be disbanded and recalled Address I EDMUND SCIENTIFIC CO. I each generation. It remained mobilized as I City Edscorp Bldg., Barrington, N.J. 08007 for a century. "The pyramids do not rep � 300 I America's Greatest Science' Optics' Hobby Mart I State Zip --- I resent an aim in itself but the means to Helping develop America's Technology for over 30 Y rs. L ______j achieve an aim: the creation of a new form of society. These huge heaps of stone mark the place where man invent ed the state." Once the state had been Now ... the most formed, once the peasant villages had enjoyable been joined under a civil service and a rule of common purpose, pyramids en do-it-yourself tered the usual budget. Post-Khufu, like I I post-Apollo, the work force dwindled project and the project was normalized. Indeed, Professor Mendelssohn proposes that we of your life too need to build a "space pyramid "; we need a great common task, and with fine A Schober Tory sentiment he feels no useful task can fill the bill. Any great useful project, Electronic Organ! he fears, can be ruined by unexpected I I side effects. Only outer space is large You'll never reap greater reward, more Join the thousands of Schober Organ fun and proud accomplishment, more builder-owners who live in every state enough and useless enough, he says, to benefit for the whole family, than by of the Union. Often starting without become the pyramid of our powerful era! assembling your own Schober Electronic technical or music skills, they have the Organ. time of their lives -first assembling, Not as novel a piece of social criticism You need no knowledge of electroniCS, then learning to play the modern King woodwork or music. Schober's com· of Instruments through our superlative as perhaps it seems (compare Lewis plete kits and crystal-clear instructions instructions and playing courses. Mumford, passim), the archaeological show you -whoever you are, whatever Get the full story FREE by mailing the your skill (or lack of it) -how to turn coupon TODAY for the big Schober color origins of this argument are fascinating. the hundreds of quality parts into one catalog, with all the fascinating details! There is much more, even a plaUSible, if of the world's most beautiful. most musi cal organs, worth up to twice the cost ------not compelling, theory of the origin of of the kit. I IThe rgan Corp., Dept. Five superb models with kit prices !J7c/lOkO SA.19 pyramid slopes, so close to 4/7r and to West 61st Street, New York, N. Y. I from $575 to around $2.300, each an 143 10023 3/7r, among surveyors apparently ignor authentic musical Instrument actually 10 Please send me Schober Organ Catalog. I superior to most you see in stores, easy 10 Enclosed please find $1.00 for 1 inch L.P. ant of the transcendental. Travelers to for any musically minded adult to learn 2- I record of Schober Organ music. Mexico will particularly profit by a to play, yet completely satisfying for the I I accomplished professional. And there I NAME I chapter on those pyramids, viewed here are accessories you can add any time as striking confirmation. There too a after your organ is finished-lifelike big :ADDRESS auditorium reverberation, automatic _. : large-scale effort justified and tested a rhythm, presets, chimes, and more . ICITY STATE _____._. ZIP ____ I strong central administration and a ncw •...... _------

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© 1974 SCIENTIFIC AMERICAN, INC concept of the state, as enduring as the reading but of writing that is the real pyramids, gain of an alphabetic way of recording. ANTIQUE Next, that crazy English orthography SYCHOLINGUISTICS AND READING, by ("ghoti" for "fish" and the like) is also in PFrank Smith. Holt, Rinehart and part rehabilitated. Carol Chomsky, in a SCIENTIFIC Winston, Inc. ($4. 95). The "monstrous paper reprinted here, observed tellingly national effort" of reading pedagogy in that the conventional written symbols the 1970's is one more load borne by mean to convey meaning clearly; they INSTRUMENTS U.S. schools in their effort to mend the need not also bring unique sounds. The damage done by the structural defects troubles implied in the words "cilia," of the American economy, now and in "kill" and "sill" are not the same as those the past. Apart from all this, a bit anx in "medicate" and "medicine." ("Words ious but genuinely engaged in helping that are the same look the same.") Spell children learn to read, this Toronto au ing is more conservative than pronuncia thor has assembled an anthology, lively, tion, and meaning often sticks with it. rather polemic and full of implications. Medikate? Medisine? Who would be Teachers and parents directly concerned helped? & Early Associated Books need these 16 chapters (a dozen of them The author ends with a wry little recent reprints by other authors with chapter in which he gives 12 golden Several hundred rare, and not so complementing and background mate rules for reading teachers, all highly rare, items from the fields of As rial), and anyone can learn in this inti plausible, many even genuinely popular tronomy, Marine Navigation, Dial mate theater a good deal about the state and in his reasoned view all dead wrong. ling Surveying, Microscopy, Pho of knowledge in the great arena of cur "Provide immediate feedback." It is a tography, and Horology are to be rent views of the human mind. bad idea, because teachers who pounce found in our new catalog. The point is sharp: Reading is not de at once on each misreading will never Please send $1 ($2 overseas) for coding from sound, nor is it primarily a find out who is reading for meaning; fully illustrated Catalog lOgE visual skill. It centers on a deeper level: such a learner tends to go back and self (available sometime in November) meaning. The printed page does not correct his errors as he comes to under even supply most of the information; we stand the text. (There is experimental HISTORICAL TECHNOLOGY read actively, building internal models proof, in case you doubt it.) One rule 6 Mugford Street that we guide, check and elaborate as Smith believes in: Respond to what the Marblehead, Mass. 01945 the string of bits Hows by. In order to child is trying to do. One can do that learn to read realistically you have to only with understanding, in reading as in. know the language, and you do not know anything else worthwhile. Psycholin 'What your home language unless you are aware of mean guistics is no panacea; heaven forfend a ing. (It goes without saying here that it is new methodological fad. What we do coula have in unlikely you can learn much until you need is understanding, and it seems common with the want to learn.) Bilingual readers absorb closer along this route than along any texts that are mixed out of two lan other on the still uncertain map. Met. the Tate. and guages, without slowing down. They the Louvre. read them aloud with errors that are DARWIN ON MAN: A PSYCHOLOGICAL translations and syntactic improvements. STUDY OF SCIENTIFIC CREATIVITY, Indeed, a skilled and successful reader by Howard E. Gruber, together with practices a sophisticated art that gives Darwin's early and unpublished note him a statistical hierarchy of options. books, transcribed and annotated by He can always drop down in sophistica Paul H. Barrett. E. P. Dutton & Co., Inc. tion, and generally he slows down as the ($20). Three men wrote this book in inti task varies, say for reading mathematics, mate collaboration. One (Barrett) is a poetry or proof. (No proofreader in En biologist at Michigan State, another glish would miss "Son cheval, suivi by (Gruber) is a Rutgers psychologiSt. They two hounds.") Meaning tells you quickly "met, as it were, across the library table." that "The none tolled hymn ..." has its On that table in the University of Cam troubles. The model of simple sequential bridge Library sat the manuscript note decoding can explain reading only at its books compiled within a couple of years AUGUSTE RENOIR's ··Claude·La Tete Baissee" lowest and slowest levels, just as a naIve long ago by a promising young scientist, Beautiful limited edition prints stimulus-response theory can explain a man of independent means then pon signed by artists whose works hang in the pigeon-pecking better than it can lan dering marriage and building in his mind world's great museums can now be yours. We offer etchings and lithographs by Picasso, guage acquisition. the framework of what is perhaps the Calder, Chagall, Dali, Renoir and other Two small surprises follow this line of most important single theoretical struc important artists, at very reasonable prices. Our expert advice and full money analysis. First of all the text is pretty ture in all science. back guarantee are your assurances that the art convincing that the Huent reading of al Darwin's making of notebooks was no you buy will have lasting value and beauty. phabetic English is not so very different personal idiosyncrasy. The six leather Send today for our free color brochure. from reading ideographic Chinese. One bound pocket books he used were "well 0ri9inal print v/ ltd/If mostly recognizes the words as wholes made manufactured articles," and his collectOrs 9rouP, and does not spell them out laboriously method of work had roots in industrial 120 East 56th Street, Dept. SA2, New York, N.Y. 10022 letter by letter. It is the digitizing not of practice, family tradition and British em-

138 © 1974 SCIENTIFIC AMERICAN, INC piricism. Although pages were later ex cised (mostly much later by Darwin for refiling), many of them still exist, and the good paper and ink preserve this inti Advice to youth mate record of a mind. The handwriting is the main technical barrier, surmounted from a science fairjudge: by "our having lived with it for a number of years." Four of the notebooks, center ing on the transmutation of species, have Winning a prize is more satisfying than been published within the past decade not winning. or so, but two of them, marked by Dar win later as being "full of Metaphysics Judges favor projects they understand. on Morals," are newly published here. Darwin on Man has two sections. The first, a little more than half the book, offers an absorbing account of the thought of that London biologist in two Even projects good enough to get all the way to the crucial years, with ample supporting dis big International Science and Engineering Fair are cussion of the intellectual setting and not PhD theses. Those who judge a PhD thesis must subtle reflection on the structure of theo be on top of all existing knowledge that directly locks ry Darwin put together. That work was no mere solving of problems, no single into the missing piece the candidate offers. Not so for great msight, but rather a productive re science fair judges. They may not be that sharply tuned construction of a few important "invari to your topic and to your every word of written and ant " elements, joined fruitfully at last by spoken explanation. They have to move along to finish a man who knew pigeon breeding as well the judging. as the Galapagos finches. In the second Photography might get through to them. Not neces section the two notebooks are given to us in full, with careful annotation by Bar sarily a dim little snapshot or two that mumbles in a " rett, the transcriber, and a running com dull tone, The follow;ng opporotus wos emploved." That you may need mentary by Gruber. Other unpublished anyway, but consider also a very short movie or a few USELESS material of Darwin's ("Old and stills that shout, "HEY, LOOK! THIS IS WHAT YOU Notes," Darwin called some of it) and a COULD HAVE SEEN!" After that, the cold facts. number of key extracts from already published material complete the book. If you have some ideas of your own, our free pack A diagram of Gruber's sets out "Dar age of photographic hints for science fair contestants win's changing world view." Before sail may prove useful. Request it from Kodak, Dept. 841, ing on the Beagle Darwin saw the world Rochester, N.Y. 14650. as two creations, the organiC world per fectly adapted to the physical. The Bea gle-and Charles Lyell's geology-made it plain that the physical world was in continuous lawful change and that the world of life had to follow. With the theory of coral reefs, drafted toward the end of Darwin's voyage, he saw that or Any questions? ganisms influenced the environment as well; the coupling was strong and the steady-state universe of Lyell therefore incomplete. Before Darwin had begun to write in the notebooks he had held, as Lamarck had, that the fitness of the liv ing world was secured by the physical in duction of biological change. Finally, in the two years before his marriage the theorist, worried but undaunted by his gradually arriving at a more materialist view of man and hence of nature, carne to see both worlds, evolving and inter At the 1974 International Science and Engineering Fair, acting. The physical world evolved by Theresa Tomilo of Comstock High, Kalamazoo, MI. showed the laws of geology, the living world by with these pictures she had taken just how hairless a hair the laws of variation and natural selec less mouse can be and what happened after injection with tion. The shifting equilibrium meant DNA extracted from embryonic cultures of haired strains. change. Only the origin of it remained She walked off with prizes and honors from the U.S. Army, for the Creator, if he existed, somewhere the U.S. Navy, and the American Dental Association, and outside the system of his works. For a a prize for photography from Eastman Kodak Company.

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© 1974 SCIENTIFIC AMERICAN, INC time, it seems, Darwin toyed with the lace late in life excluded man from evo continuous generation of life, before his lution; the mind, he held, was spiritual What IOU ShOUld rereading of Malthus gave him the last in its nature and origin. push to his deeper structure. In Novem Darwin's life, the scientist's Rama know about man's ber, 1838, his notebook says: "Three yana, to be reviewed and celebrated in most baUling eneml principles will account for all (1) Grand every form and style, is well served by VIRUSES by David M. Locke children like grandfathers (2) Tendency this book. Darwin admirers and all stu covers the chemistry of viruses to small change especially with physical dents of the 19th century will need it. and their effect on our lives, how change (3) Great fertility in proportion Other readers in search of how ideas they cause disease and interfere with cell machinery, how they are to support of parents." It was clear arise will find it a prize case study, as combated by the body and by enough, even though the puzzling black free of simplistic naivete as of strong pre drugs, the virus-cancer relation box of variation waited for genetics to conception. And what biologist can re ship, the research being done open it. sist the man who wrote in his notes: "The around the world, and much more. Most of the text is given over to Dar grand Question which every naturalist Illustrated. Over 500 pages. win on man, important because it early ought to have before him when dissect $10.95, now at your bookstore. or send check or money order to CROWN PUBLISHERS, and plainly goes to his perception of the ing a whale or classifying a mite, a fun 419 Park Ave. South, New York, N.Y. 10016 unity of life, in which anatomy and be gus or an infusorian is 'What are the havior, and with behavior mind, were Laws of Life.' '' woven into one fabric. "The problem of the mind cannot be solved by attacking EllA VIOUR OF MICRO-ORGANISMS, co- the citadel itself.-the mind is function of B ordinated by A. Perez-Miravete. body.-we must bring some stable foun Plenum Press ($19.50). No scientific edi dation to argue from." Explicit self tor reviewed these 25 papers, so that the awareness, trips to the primates at the name appearing in the editor's place is zoo, a marvelous paper on the behavior that of the scientist who coordinated all of his first-born infant William and final the publications reporting the Mexico ly the late books The Descent of Man City Congress of Microbiology a few and The Expression of the Emotions in years ago, from which these contribu Man and Animals all bear witness to the tions stem. The authors-microbiologists depth and intensity all his life of the from all over the U.S. and from Europe ideas first examined in the intimate note and Japan-are solely responsible, al books presented here. They are by no though the papers have been given a means "Victorian" but rather are medi pleasingly consistent appearance. cally frank. (Darwin's father was, after Here is psychology at its farthest limit. all, a rationalist practicing country doc The known behavior of single-celled tor, no prude and no diplomat.) "Sexual forms-bacteria, algae, pollen, protozoa desire makes saliva to flow / yes, cer and spermatozoa are all included-is not tainly / curious association ... ones tend complex. Motion is almost the only re ency to kiss, & almost bite, that which sponse we can detect; it can be more or one sexually loves." There is room for less speedy, a mere creep or as slow as study of the unconscious personality of growth. A pollen tube just microns across this young man, but what we have be grows down a length of the cornstalk to fore us is quite the reverse, a document hit its target embryo nearly two feet ed and clear effort to follow the branch away within one day. There is chemical ing and flowering of his explicit ideas. guidance, all right, but the means re The authors plainly love him, this man main obscure. Early workers saw that transparent and open to his friends, yet animal sperm cells similarly found their assuming a quiet, nonpolemic, guarded egg targets, but they steadily confused stance ina world where his views meant the effects of such simple factors as egg intellectual warfare. Here is no neurotic secretions, which tended to immobilize victim of a tyrant father, no timid rec even rather distant sperm, with a crowd luse, no hypochondriac, whether in of successful spermatozoon navigators. these years or later. Thought, like the Even in 1966 it was still learnedly held k ingdom of life, grows and evolves slow that cells as small and simple as the ly; the book focuses on "the inner work sperm-from which each reader gets of synthesis"and not on the claimed half of his or her genetic legacy-could satori of one chance page. It is interest not seek out their target save by random ing to recall that Darwin read Malthu s means. Drawings made from frame-by ARCHAEOLOGY-Dept. SA 260 West Broadway, New York, NY 10013 in quiet London reflectionyears after frame films here clearly exhibit sperm (of $8.50-1 year $15-2 years $22-3 years his field contact with the Galapagos; certain marine hydroids) swimming Add $1 per year for foreign postage. his counterpart Alfred Russel Wallace straight as a die to a tiny mass of agar Please send ARCHAEOLOGY to: thought of Malthus over many years but impregnated with an extract of the egg.

a e ______N m __ produced his syntheSiS of natural evolu Bacteria detect chemical gradients Address ______tion only while he was living in the very and move toward them. They are dis

______Zip ______islands where he made his observations criminating; the colon bacillus Esche on the diversity of tropical species. Wal- richia coli, for example, can detect at

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© 1974 SCIENTIFIC AMERICAN, INC least eight different substances. How? We do not know. Whether protozoa can learn, and even what that might mean, is still not well established. When the protozoon no longer responds to repeat INDEX OF ADVERTISERS ed mechanical shock (a controlled ping ing at the edge of the microscope slide), OCTOBER 1974 it is learning very little; on a more fa miliar scale we might suspect it is just ALUMINUM COMPANY OF AMERICA 74 LIBRARY OF SCIENCE, THE ...... 134 Agency: Fuller & Smith & Ross, Inc. Agency: Henderson & Roll. Inc. getting tired. Can it be conditioned like Pavlov's dog? Can it discriminate several ALLIED CHEMICAL CORPORATION 11 9 LUFTHANSA GERMAN AIRLINES Agency: J. S. Lanza & Associates (Inl.) ...... Back Cover stimuli? Not yet known. There are inter Agency: H. K. McCann Company mbH ALMADEN VINEYARDS 4 nal clock rhythms on this scale of being, Agency: Dancer Fitzgerald Sample, Inc. MAKER'S MARK DISTILLERY ...... 56 and they can be reset and entrained. Agency: Doe-Anderson Advertising Agency, Inc. AMERICAN I RON & STEEL INSTITUTE 59 Light too can induce motion in cells too Agency: Hill and Knowlton, Inc. MERCEDES-BENZ AG (Inl.) .Inside Fronl Cover, small to boast an eye; some blue-green AMERICAN MANAGEMENT Agency: Huemann, Ogilvy & Mather G.m.b.H. algae steer toward the light, although ASSOCIATION (Inl.) ...... Agency: Schwab. Beatty & Porter, Inc. MERCEDES·BENZ OF NORTH AMERICA, some simply bask in it once they get INC. .8,9 ARCHAEOLOGY MAGAZINE . 140 Agency: Ogilvy & Mather Inc. there by a random walk. Euglena, a true AUSTIN, NICHOLS CO., INC. .12, 98 nucleated alga, possesses an eye spot, & MINOLTA CORPORATION 58 Agency: Nadler & Larimer, Inc. and it can seek or shun light as it chooses Agency: E. T. Howard Company, Inc. BAUER, EDDIE, EXPEDITION OUTFITTER 56 MOBIL OIL CORPORATION .60, 61 (if it can choose). It is no crude detector; Agency: 10hn L. Kime Advertising only four photons absorbed are enough Agency; Doyle Dane Bernbach Inc. CARILLON IMPORTERS ...... to induce a perceptible reaction! Agency: Martin Landey, Arlow Advertising Inc. MONTRES ROLEX SA (Int.) The collection includes five papers on Agency: J. Walter Thompson Company Ltd. CASIO, INC...... 71 the interesting nature of the flagella or Agency: Doremus & Co. NATIONAL CAMERA, INC. 136 the cilia. Except for the jellylike amoe Agency: Langley Advertising Agency CHRYSLER CORPORATION, CHRYSLER bas, which appear to contract internally PLYMOUTH DIVISION 62 OLYMPIC SALES CORPORATION 105 and thereby to ooze themselves along Agency: Young & Rubicam, Inc. Agency: Tom Brigham & AS"Iociates

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© 1974 SCIENTIFIC AMERICAN, INC A GAS HEATED FURNACE. Nathan TERNED ORGANIZATION. Emilio Bizzi, BIBLIOGltAPIIY Gilbert and Farrington Daniels in In Ronald E. Kalil and Vincenzo Tagli dustrial and Engineering Chemistry, as eo in Science, Vol. 173, No. 3995, Vol. 40, No.9, pages 1719-1723; Sep pages 452-454; July 30, 1971. Readers interested in further reading on tember, 1948. ADJUSTMENT OF SACCADE CHARACTER the subiects covered by articles in this RADIATION CHEMISTRY OF THE FIXATION ISTICS DURING HEAD MOVEMENTS. P. issue may findthe lists below helpful. OF NITROGEN. P. Harteek and S.Don Morasso, E. Bizzi and J. Dichgans in des in Science, Vol. 146, No. 3640, Experimental Brain Research, Vol. 16, THE INTERNATIONAL CONTROL pages 30-35; October 2, 1964. pages 492-500; 1973. OF DISARMAMENT BIOLOGICAL NITROGEN FIXATION. R. W. MECHANISMS UNDERLYING RECOVERY OF F. Hardy and R. C . Burns in Annual EYE-HEAD COORDINATION FOLLOWING SECURITY IN DISARMAMENT. Edited by Review of Biochemistry, Vol. 37, BILATERAL LABYRINTHECTOMY IN Richard J.Barnet and Richard J. Falk. pages 331-358; 1968. MONKEYS. J. Dichgans, E. Bizzi, P. Princeton University Press, 1965. Morasso and V. Tagliasco in Experi STUDIES IN WAR AND PEACE. Michael TIlE DIMENSIONS OF STAIRS mental Brain Research� Vol. 18, pages Howard.Viking Press, 1971. 548-562; 1973. THE GAME OF DISARMAMENT. Alva ACCIDENTAL INJURIES DUE TO FALLS. Myrdal in Impact of Science on So Dan D. Gowings in National Safety THE EXCAVATION ciety, Vol. 22, No.3, pages 230-231; Congress Transactions, Vol. 6, pages OF A DROWNED GREEK T EMPLE July-September, 1972. 59-62; 1960. CHEMICAL DISARMAMENT: SOME PROB TELEMETERING ELECTROMYOGRAPHY OF BALLOON OVER SARDIS. Archaeology, LEMS OF VERIFICATION. Stockholm MUSCLES USED IN WALKING UP AND Vol.20, No.1, pages 67-68; January, International Peace Research Insti DOWN STAIRS. J. Joseph and R.Watson 1967. tute, 1973. in Journal of Bone and Joint Surgery, SHALLOW-WATER EXCAVATION AT KEN Vol. 49 B, No. 4, pages 774-780; CHREAI. Joseph W. Shaw in American THE STRUCTURE 1967. Journal of Archaeology, Vol.71, No.3, OF EMISSION NEBULAS OPTIMUM DIMENSIONS FOR DOMESTIC pages 223-231; July,. 1967. STAIRCASES. Joan S. Ward and Wil BALLOON OVER HALIEIS. Julian Whittle ATOMS, STARS, AND NEBULAE. Lawrence liam Beadling in Architects' Journal, sey in Archaeology, Vol. 21, No. 1, H. Aller. Harvard University Press, Vol. 151, No. 8, pages 513-520; Feb pages 66-67; January, 1968. 1971. ruary 25, 1970. EXCAVATIONS AT PORTO CHELl AND VI PLANETARY NEBULAE. L. H. Aller. Sky PEDESTRIAN PLANl'.'ING AND DESIGN. John CINITY, PRELIMINARY REPORT, I: H A and Telescope, 1971. J. Fruin. Metropolitan Association of LlEIS, 1962-1968.Michael H. Jameson AsTROPHYSICS OF GASEOUS NEBULAE. Urban Designers and Environmental in Hesperia, Vol. 38, No. 3, pages D. E.Osterbrock. W. H. Freeman and Planners, 1971. 311-342; July-September, 1969. Company, 1974. ARCHAEOLOGY UNDER WATER. George F. PLANETARY NEBULAE. J. S. Miller in An MII\UCRY IN PARASITIC BIRDS Bass.Penguin Books, 1972. nual Review of Astronomy and Astro physics, Vol. 12; in press. CHARACTER DISPLACEMENT. W. L. MATHEMATICAL GAMES Brown, Jr., and E. O. Wilson in Sys HOW CILIA MOVE tematic Zoology, Vol. 5, pages 49-64; THE THEORY OF COMMITTEES AND ELEC 1956. TIONS. Duncan Black. Cambridge STUDIES ON CILIA-III: FURTHER HOMAGE TO SANTA ROSALIA, OR WHY University Press, 1958. STUDIES ON THE CILIUM TIP AND A ARE THERE SO MANY KINDS OF ANI VOTING AND THE SUMMATION OF PREF "SLIDING FILAMENT" MODEL OF CILI MALS? G. E. Hutchinson in The Amer ERENCES: AN INTERPRETATIVE BIBLI ARY MOTILITY. Peter Satir in The ican Naturalist, Vol. 93, No. 870, OGRAPHICAL REVIEW OF SELECTED Journal of Cell Biology, Vol. 39, pages pages 145-159; May-June, 1959. DEVELOPMENTS DURING THE LAST 77-94; 1968. EVOLUTION IN CHANGING ENVIRON DECADE. William H. Riker in The ADENOSINE TRIPHOSPHATE-INDUCED MENTS. Richard Levins. Princeton American Political Science Review, SLIDING OF TUBULES IN TRYPSIN University Press, 19G8. Vol. 55, No.4, pages 900-911; De TREATED FLAGELLA OF SEA-URCHIN ON THE 1\1ETHODS OF RESOURCE DIVI cember, 1961. SPERM. Keith E. Summers and I. R. SION IN GRASSLAND BIRD COMMUNI TOPICS ON TOURNAMENTS. John W. Gibbons in Pl'Oceedings of the Na TIES. Martin L. Cody in The American Moon. Holt, Rinehart and Winston, tional Academy of Sciences of the Naluralist, Vol. 102, No. 924, pages 1968. United States of America, Vol. 68, 107-147; March-April, 1968. No. 12, pages 3092-3096; December, THE AMATEUR SCIENTIST 1971. THE COORDINATION CILIA AND FLAGELLA. M. A. Sleigh. OF EYE-HEAD MOVEMENTS ATMOSPHERIC ELECTRICITY. J. Alan Academic Press, 1974. Chalmers. Pergamon Press, 1968. CENTRAL CONTROL OF MOVEl\1ENT ELECTROSTATIC MOTORS: THEIRHIS NITROGEN FIXATION NEUROSCIENCES RESEARCH PROGRESS TORY, TYPES AND PRINCIPLES OF Op BULLETIN: VOL. 9. Edited by E. V. ERATION. Oleg D. JeRmenko. Electret THE SYNTHESIS OF AMMONIA FROM ITS Evarts, E. Bizzi, R. Burke, M.DeLong ScientiRc Company, 1973. ELEMENTS. Fritz Haber. Nobel Lec and W. T. Thach, 1971. ELECTROSTATICS AND ITS ApPLICATIONS. ture, June 2, 1920. EYE-HEAD COORDINATION IN MONKEYS: Edited by A. D. Moore. John Wiley & FIXATION OF ATMOSPHERIC NITROGEN IN EVIDENCE FOR CENTRALLY PAT- Sons, 1973.

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Q. Mr.Cronkite, whyis it good business for a U.S. Corporation to help in the education process of people in less developed countries? A. We ace not alone on this planet. Om rutme people in developing countries can be raised, with far is closely related to the continuing development of all reaching results for them and indirectly for all of us. people. Through massive relief and technical assis There is an organization that can assist your corp tance projects we are providing food and clothing to oration in this vital educational process. deserving people ... but that is not enough. They also Franklin Book Programs, Inc. is a nonprofit or are hungry for knowledge and for long range self ganization for international book publishing and edu development tools. cational materials development that has been serving Education is the key to progress in less developed successfully since 1952. It is an organization which I countries, as it was in the development of our own have been associated with for the past 8 years, as a country. School and reference books, audio-visual ma Member of the Board of Directors and presently as a terial, self-help information, even fun books for chil Member of the Corporation. drenare a scarce commodity in most developing coun You and your Corporation Contribution Commit tries ...and especially in their own languages of Ben tee should know more about the worldwide educa gali, Urdu, Arabic, Farsi and Spanish. tional scope of Franklin. I hopej!dJr that you will The cooperation of U.S. Corporations is needed in join with me in supporting their this educational process to create a better informed efforts to hel p others world. Through education the standard of living of help themselves.

To receive an annual report and for further information, please call 212-68]-2500 or write to: Franklin Book Programs, 801 Second Avenue, New York, N.Y.IOOI7

How Exxon is squeezing additional oil out of a 55-year-old field.

A popular myth has it that oil is enough 10 move the oil to the well. covery waterflood project, which found in large underground lakes Or, over time, they may have dimin has since cost about $20 million. or pools. Actually, when oil and nat ished to the pOint where they must Engineers now estimate that the ural gas are discovered they are be supplemented by additional Hewitt field ultimately will produce inside sedimentary rock. They are pressure. This additional pressure 35% of the original oil in place. trapped in the tiny pores of lime is provided by "secondary recov Without the use of waterflooding, stone or sandstone as far as five ery" methods. total recovery had been estimated miles underground. at only 20%. Forcing water deep Usually, when a well is drilled into the oil-bearing rock. Sometimes, but not at Hewitt, nat into oil-saturated rock, natural un The most widespread secondary re ural gas is injected instead of water. derground pressures force the oil covery method in use throughout However, the efficiency of water to flow through the rock to the well the oil industry is waterflooding, flooding usually makes it more and then to the surface. which was introduced over 30 years attractive. However, in many oil fields these ago. Water is pumped into the oil natural pressures are not strong An experiment using heat and bearing rock to flush out more of subterranean "detergents:' the oil than would be produced by Even after an oil field is subjected natural, or primary forces. to secondary recovery techniques, On the average, natural pres such as water and gas injection, a sures move only about 15-20% of a large percentage of the oil still re field's oil from the underground mains locked in the pores of the rock up to the surface. By using rock. So for many years, Exxon has· secondary recovery technology, been experimenting with tertiary re the final yield can be increased to covery methods designed to re an average of about 35%. cover more of this oil. The Hewitt Field-a case in point. In one experimental process, a The Hewitt oil field, discovered in "d etergent" or surfactant is 1919, near Ardmore, Oklahoma, is pumped into the rock. This agent operated by Exxon and several works like a laundry detergent that other companies. Originally, this removes oil from a shirt-it flushes field produced nearly 30 thousand out the droplets of oil which still barrels of oil a day. However, the de remain in the pores of the rock. In pletion of natural underground some cases, particularly where the pressures gradually reduced Hew oil is thicker, sometimes nearly the Sample drilling cores taken tram oil-saturated itt's production to the paint where consistency of molasses, steam in rock lormations in Alaska, Texas and the field needed waterflooding. jection also is being tested. The hot Saudi Arabia. Oil and gas must come Irom and flow through rock like this belore they reach In 1969, Exxon and other owners steam heats the oil, making it flow the well bore. began a cooperative secondary re- more freely.

© 1974 SCIENTIFIC AMERICAN, INC Artist's conception 01 the Hewitt oil lield located near Ardmore, Ok/ahoma. Large quantities 01 water are being injected into the oil-saturated rock to signilicantly increase the oil production.

In perhaps the most dramatic oil A realistic look at the future. But scientists believe that experi recovery technique, air is injected To date, about 450 billion barrels mental "tertiary" techniques like into the rock formation holding the of oil have been found and docu "detergents" and combustion , oil. This injected air supports con mented in the United States. Even could someday produce a signifi trolled underground combustion, after additional recovery efforts, cant amount of additional oil which which heats the oil, causes it to flow like the waterflooding at Hewitt, are America will need in theyears ahead. more readily and drives it to the well. applied, some 300 billion barrels In addition, Exxon is testing and of this oil will still remain locked in evaluating several other tertiary the pores of rock. Today, there is techniques. no way to recover all of this oil.

If you've found that a lot of small cars today are pretty small on comfort and style, then the '75 Dart Special Edition is the small car for you It has an array of standard features that are usually anything but standard. Seats covered with crushed velour upholstery. Plush carpeting on the floor, halfway up the door, and even in the trunk. Map pockets are standard. So are color-keyed wheel covers. And front disc brakes. And power steering. Even the radio is standard. In other words, on the '75 Dart Special Edition, luxury comes as standard equipment. And, as on all the '75 Darts, there are a lot of money-saving engineering features such as Electronic Ignition and electronic voltage regulator and, now for 1975, an optional fuel pacer that can help you save gas. Today, over one million satisfied owners are already sold on Dart. Th e '75 Dart Special Edition is one beautiful way to make sure there'll be one million more.