4 SCIENTIFICAMERICAN SUPPLEMENT NQ 2270 July 5, 1919

Lignum-Vitae, the Vital Wood The Most Important Single Wood for the American Navy and Merchant Marine

By Samuel J. Record, Professor of Forest Products, Yale University

WHAT woods contributed most to the winning of the when it becomes waterlogged, that is, when the buoy­ and serves as a natural lubricant to the revolving shaft. war? There was spruce for airplanes, black walnut ant air in its cellular spaces has been replaced with The density of the wood enables it to withstand enor­ for gunstocks, oak and hickory for vehicles and gun water. Take balso wood, for example, which during mous loads; the interwoven fiber keeps it from splitting carriages, mahogany for airplane propellers, yellow the war was used extensively in making the big life and tearing apart under impact; the infiltrated lubri­ pine and Douglas fir for ships. Of these woods and rafts so conspicuous on every transport and battleship. cant prevents friction and eliminates the danger of their uses the public has heard, but there is another, Balsa is as light as cork when dry, but unlike cork, an overheated bearing. one of the most important of all, which has escaped which is waterproof, it absorbs water readily when in The stern tube, in which the propeller shaft revolves, public notice. This is not surprising since this wood a natural condition. This tendency is overcome by extends from the peak bulkhead in the after-part of performs its duties, silently and efficiently, in the most sealing up the air with a light impregnation of para­ the hull to the stern post and, in a large steamship, secluded position imaginable. ffine. Balsa and lignum-vitae represent opposite is usually from 5 to 7 feet long and from 12 to 22 or The propeller shaft of every battleship, every cruiser, extremes in tropical woods, nature apparently experi­ even 30 inches in diameter. The forward end is made every destroyer, every transport, in fact of every large menting to find out how little wood sUbstance she water-tight by means of a stuffing box and flange but steamship revolves in wooden bearings. And of all the could use in one and how much in the other. the after-end, in the usual construction, is left open thousands of woods in the world, just one has been Nature could not make an absolutely solid wood to the water. found equal to these exacting requirements. And that because she had to leave spaces and channels for sap- The stern tube is composed of three parts, namely, is true lignum-vitae, na­ (1) an outer steel tube tive of the West Indies with (2) a brass or and certain other parts bronze bushing or sleeve of tropical America. with longitudinal cleats This important bearing or retaining strips which is in the stern tube in the hold in place (3) the after part of the ship, lining of e d g e - g r a i n next to the screw itself, wooden bearing blocks. where only a substance The number of retaining able to withstand great strips varies in different friction could possibly forms of construction. last for any length of There may be only one in time. It sustains not which case it is located only the enormous dead at the upper part of the load of the propeller tube; or two, one at each shaft and that of the pro­ side; three, one at each peller, which may weigh side and one at the top; as much as 9 tons, but or as many as there are also withstands the ter­ rows of blocks, in some rific impact from the instances 24. In the first pounding of high seas. methods the lining be­ And this it will do for tween the retaining strips years in a submerged po­ is of much the same sition where no external structure as a wooden­ lubricant can reach it stave pipe, each stave In except water. this case being a row of Lignum-vitae possesses edge-grain blocks placed certain peculiar proper­ end to end, beveled along ties which fit it for this the side and machined on exacting requirement and the faces to fit the bore unfit it for nearly all the of the tube. uses to which other The retaining strips woods are put. First of serve not only to hold Bark of Cuban lignum -vitae Bark of Haitian lignum-vitae all, it is the most cross­ the blocks In place but grained wood in the also provide grooves into world and comes as which water enters. The near being woven as it is water serves the dual possible for a wood to be. purpose of cooling and The fibers never run lubricating. Where the straight up and down the rows of blocks are ar­ log but weave back and ranged in a solid layer It forth in a serpentine is considered a good manner in thin layers or practice to ('ut V-shaped plies that cross and grooves at the joining criss-cross like the corded lines to act as waterways. fabric of an automobile There are two princi­ tire. The result is a ma­ pal methods of preparing terial of extreme tenaci­ the blocks for stern ty and toughness. bearings. In one the In most woods used logs are cross-cut Into where strength is de­ short blocks or "pan­ manded, cross-grain is a cakes," the thickness (In serious defect. For ex­ direction of the fiber) ample, in selecting spruce varying from 1 to 2 for wing-beams of air­ inches according to the planes the great demand size of the stern tube. Cross section of Guaiacum from Haiti was for straight-grained Cross section of Bulnesia arborea (Maracaibo) These "pan-cakes" are Note irregular distribution of the pores Note the radial distribution of the pores material and only a then sawed into rectangu- fraction of the lumber lar blocks from 2 to 4 produced from the choicest trees would meet the re­ flow, but she found a way to overcome this difficulty. inches wide, not less than 4 inches long, the maximum quirements. Danger lurked in every cross-grained As soon as the old cells cease to function their every lengths being determined by the diameter of the heart­ piece and for an inspector to let such a specimen get nook and cranny is filled up with a resin which is wood portion of the log. As soon as the blocks are past him was little less than a crime. Perhaps at the about a third heavier than water. The result is a sawed out they are dipped in shellac to prevent check­ same time an inspector in a shipyard was condemning material weighing about 80 pounds per cubic foot ing and warping prior to use. a poor grade of lignum-vitae because it was not cross­ which is 10 times as much as balsa, 3 or 4 times as There is a large amount of waste in cutting out these grained enough! much as spruce and 1* times as much as white oak. blocks, being about 33 per cent. In logs 16 inches and A11 of our ordinary woods will float when dry, but Since lignum-vitre sells by weight, sometimes for as over in diameter, about 50 per cent. in those between lignum-vitae will sink like a stone even when every high as 52 cents a pound, it is obviously a valuable 12 and 16 inches, and as high as 75 per cent. in the particle of water has been removed from it. The commodity. smaller sizes. On this account a minimum diameter of substance of which all woods are made is about the It is to this resin content, this after-thought of na­ 12 inches is usually specified. It is also claimed that same and weighs half as much again as water, hence ture, that lignum-vitre owes its high rank in the marts logs of the larger diameters yield better and particular­ one dry wood is light and another heavy for the same of the world. Herein lies the secret of Its success as ly more resinous wood. The wood close to the pith is reason that snow is lighter than solid ice. bearings in a most trying position, for this resin serves avoided because of the danger of checking, while the The lightest wood known will sink like a plummet to protect the wood from the softening effect of water sapwood is not used because it lacks the necessary resin.

© 1919 SCIENTIFIC AMERICAN, INC. July 5, 1919 SCIENTIFIC AMERICAN SUPPLEMENTNo. 2270 5

In the second method the logs are cut into cants or provides one outlet for the defective and crooked logs of testimonials to its curative powers, and the many planks of the required thickness and as wide as the which are to be found in every shipment. The selling failures were ignored or explained away. diameter of the heart-portion of the log will allow. price, delivered to residences, is about $25 a ton. This wood was called by the natives "guayacan," These cants are then placed edgewise on an adjusta­ The sawdust or flour obtained in cutting up the but the Europeans re-christened it "lignum-vitoo," the ble frame rotating about a fixed center on the table of wood in manufacture is in demand by the drug trade wood of life, and by this name it is still known through­ the band saw. In this way the blocks are cut with a t a price varying from $20 to $40 a ton. From this out the timber markets of the world. The old name, the proper degree of curvature to fit exactly into the the resin is extracted and while some of this finds its latinized to Guaiacum, is retained for botanical and sleeve. The blocks are then beveled. and cut in two way to the druggists' shelves to fill an occasional pre­ pharmaceutic purposes. lengthwise with a slight taper to permit "fox-wedging" scription for gout or rheumatism, its principal demand Lignum-vitoo is today medicinally obsolete. The one into place. This method of fastening in the blocks is is in the manufacture of the compound decoction of ingredient to which it owed its healing power has shown by the cross-section below. sarsaparilla. There is nothing in its present lowly been lost, and that ingredient is Faith. After the blocks are fitted, wooden strips are tem­ estate medicinally to suggest the glory of earlier days Lignum-vitoo's present value and reputation are ' porarily placed in the grooves, and the tube is fixed when it was hailed as a panacea of all man's ills and founded on more substantial and enduring grounds. in a lathe and bored out to the exact diameter re­ commanded as much as seven gold crowns a pound. For its more important uses no satisfactory substitute quired to fit the propeller shaft. To prevent the blocks Here is the story: has been found. This brings up the question of drying out and checking or getting loose supply. How long will the present source the tube is kept filled with wet sawdust hold out and what new fields are awaiting and shavings until permanently installed development? in the ship. The life of a ligum-vitoo bearing is said PRESENT SOURCES OF SUPPLY. to be about 10 years. If the propeller Several different kinds of lignum-vitre shaft is out of alignment it may wear are recognized by the trade and they are out the bearing in two years or less. The usually designated by the name of the greatest wear is sustained by blocks in eountry or the port of origin. The prin­ the lower part of the bearing since these cipal kinds now found on the New York support the most of the weight, not only of market are Cuban, San Dominican, Ja­ the shaft, but also of the propeller which maican, Haitian and Nicaraguan. Others may be as great as 9 tons. When to this less common are Bahaman, Mexican and dead load is added the impact of the South American. Buyers generally specify waves it is obvious that only the densest the kind of wood they want and their and most tenacious woods would be able likes and dislikes are usually very de­ to withstand the enormous strains pro­ cided. To what extent these opinions duced. Various woods have these prop­ are based on facts and to what extent erties but none other than ligum-vitoo they are mere prejudices the writer has combine with them the natural lubricant been unable to determine, but they do ex­ indispensible to the prevention of heating ist and exert a very material influence on and rapid attrition. the market and have a very important Small bushings are sometimes bored from bearing on the question of future supply. solid wood instead of being built up. The Cuban lignum--vitoo is considered the process of manufacture of the so-called standard, at least for the larger sizes. "patent feathering wheel bushings" which Bark of Nicaraguan lignum -vitae The logs are mostly 4 to 8 feet long with are used on certain side-wheel steamers The wood is used in the United States, but not in Europe a few of the smaller sizes 10 feet. The is as follows: The logs are cut into bolts diameters range from 6 to 24 inches with 16 to 18 inches long, slabbed to an octag­ only a small percentage over 16 inches. onal form to remove the sapwood, and Logs of assorted sizes have recently been then turned in a lathe to a diameter of sold alongside the railroad in Cuba for as 5 1/16 or 5\18 inches. These cylinders are high as $135 a ton. Most of the Cuban then cut into 7-inch and 8-inch blocks and wood is obtained from Oriente Province the centers bored to the required size. in the eastern part of the island and is The manufacture of stern bearings shipped from Santiago. According to a calls for the highest quality of logs and Commerce Report of 19 17 not more than these now command a price of from 1� 4,000 tons remain in accessible places, not to 18 cents, mostly 14 to 16 cents, per more than one-third of this would repay pound. At 15 cents a pound, a cubic foot the cost of getting it out, and the total weighing 80 pounds is worth $12. In supply is in danger of early exhaustion. some instances lignum-vitoo has been sold A New York dealer questions this state­ for as much as 25 cents a pound or about ment and cites the fact that a single op­ $20 per cubic foot. erator in this region got out 1,000 tons Stern bearings provide the most impor­ in 1918 and that others were also engaged tant use for lignum-vitoo but by no means in the business. There is also some wood the only one. Formerly it was in great in the Pinar del Rio Province in the west­ demand for bowling balls but now only ern part of the island but it is not now about one ball in ten is made of wood. being exploited. There is plenty of Cuban The value of the lignum-vitoo block from lignum-vitoo available now but only con­ which a "regulation" ball is cut is about tinued high prices will justify the diffi­ $2.50 and the manufacture requires much cult logging of the remaining standing skill and painstaking effort. timber. A large quantity of low grade logs, The lignum-vitre from Jamaica, Ba­ known as "cutting up" wood, is consumed hama Islands and Porto Rico is small, in the manufacture of rollers for furni­ usually not exceeding 5 inches in diam­ ture casters. Small round sticks make eter. It is of good quality and is chiefly excellent mallets and fill a large demand, in demand, for mallets. The supply is especially in England. Another impor­ limited but will last for many years if tant use is for sheaves of pulleys, and they the demands upon it are not heavier than have been known to last in constant use Cross sections of stern tubes of different types they have been. for 70 years. Wooden sheaves are never At left a large stern tube with waterways between the strips of lignum-vitae blocks. Below a strip of blocks in position showing lengthwise cut to permit wedging into place. There are two distinct grades of wood used with steel cable or wire rope. An­ 3 At right: above, section of tube of a steam trawler showing solid lining with retaining from the island of Santo Domingo. That other nautical application is for "dead­ strips and waterways; below, section of a small tube, with single retaining strip at top and between the blocks. eyes," .a small flattish block with a grooVJeS for waterways cut obtained from the Dominican Republic is grooved rim to fit in the bight of a rope recognized as genuine and has the char­ or encircled by an iron band, pierced with three holes Some 400 years ago Gonsalvo Ferrand, a Spanish acteristic bark and other features of the Cuban. The to receive a lanyard, and used to extend the shroudl'l explorer found in the West Indies a squatty, thick­ logs now reaching the market are from 2 to 3 feet and stays. boled tree with a wood reported by the natives to have long and mostly 4 to 10 inches in diameter. It is said Among the miseellaneous uses may be mentioned great curative powers. The mind of the visitor was that much larger wood than is now being obtained i,,; stencil and chisel blocks, watch-makers' blocks, mor­ ripe for miracles and here was the beginning of one. available in considerable quantity in this_ country, but tars and pestles, dowels, golf-club heads, wooden cogs, When his ship returned it carried in its hold a few that the natives lack the necessary facilities and roads water wheels, and block guides for band saws. In short logs of this wood the medicinal virtues of which for getting it out. This is a promising future source building the Panama Canal, the true lignum-vitoo waxed mightily with every re-telling. of supply and some wood users consider the wood fully made the most serviceable railroad cross-tie that could Arrived in Europe this wood met instant favor with as good if not better than Cuban. be obtained. If not spiked to death, such a tie will the medical fraternity and was hailed as a god-send Lignum-vitoo is scattered over the whole of Haiti, last 30 years under the most trying conditions. to humanity. From the New World had come a rem­ but most of it that reaches the market is considered Between 150 and 200 tons of genuine lignum-vitre edy for such great scourges and maladies as lues by dealers and users as non-genuine and is often called are used every year in New York for .fuel in grate venerea, leprosy, scrofula, palsy, epilepsy, gout, chronic "bastard lignum-vitoo" in the trade and "vera " or fires. The very dense nature of the wood together rheumatism and many other diseases. Learned trea­ "bera" locally. It is unquestionably a species of Guaiacum Bulnesia with the heavy resin content produces a fuel with in­ tises began fo appear as early as 1517 and were many and not of the closely related genus tense glowing heat and of good lasting qualities. This times reprinted and translated. There was no dearth (Continued on page 15 )

© 1919 SCIENTIFIC AMERICAN, INC. July 5, 1919 SCIENTIFIC AMERICAN SUPPLEMENTNo. 2270 15 shaped, was kept in a bottle of dry radium bromide magnet, and a current of 30 amperes was passed inches. They are straight, smooth and cylindrical and for !lome weeks until it was quite green. By met�ns of through for three hours. The current was then ;;hut free from defects except end checks wMch give l.\ a steel wheel fed with diamond dust part of one face off, and the film shifted sideways for half an inch, bad appearance but generally do not penetrate deeply. was cut away, and the surface of an adjoining face and the action of the diamond without the magnetism The amount of lignum-vitre coming out of Mexico was just removed, the adjoining corner thus being was allowed to go on for another three hours. It was is at present very small. The writer had occasion to freshly exposed diamond crystal. It was put on a then developed, :tnd both spots hppeared about the inspect a carload of logs from the northwestern part sensitive film in such a position that it could be sub­ same intensity. of the country and found them of various lengths up to sequently examined and compared with the developed 25. The diamond crystal (17) in its brass box had 6 feet and ranging in diameter from 8 to 11 inches. image, so that the active portions of the surfaces, a thin plate of clear mica put over the hole, and a They were all more or less faulty, being crooked, natural and ground off, could be seen. It was allowed sheet of lead over that. All was wrapped in sheet gnarly and knotty, with wide sap and small hearts to act for five days, when the film was developed. The lead, and so kept for about six months. There was an which were often affected with rot. The writer was result indicated very decidedly that where the surface extremely faint but hardly appreciable darkening of unable to determine whether or not this shipment was of the diamond had been removed it was no longer the mica at the position of the hole. typical of the region. radio-active (13). 26. After the above experiment the diamond was kept in its brass box for two years, and then laid on FUTURE SOURCES OF SUPPLY. EXPERIMENTS WITH A VERY ACTIVE DIAMOND CRYSTAL. a sensitive film and kept for three hours. On devel­ The West Indies will probably continue to supply 17. A fine crystal of diamond from Kimberley whicll oping a spot of action was seen, showing that the the bulk of the high-grade lignum-vitre for many years had been kept in a bottle of radium bromide for some diamond was still radio-active. It was removed from if priCes remain at sufficiently high levels to warrant 1Il0nths was tested on a sensitive film and in the ell�c­ its brass cell and examined in the dark on a bIen de the increased expense attending the more and more troscope. It was found to be highly aetive, and was screen. It gave plenty of scintillations easily visible difficult logging. Improvement of the transportation set aside for further experiments. It was luminous in without a lens. Experiments showed that it still gave facilities and logging methods in certain regions will the dark, quickly discharged the electroscope, and out, along with a-rays, also (3-rays and y·rays (10, 19, permit the getting out of material now too large to caused an inactive diamond held near it to phospho· 42, 43). be handled in the primitive native manner over rough resce. It was put on the surface of a screen coatel1 27. A small light-tight box was fitted as a camera. trails. with small crystals of barium platinocyanide, and The arrangements were such that the image on the There is believed to be a large supply of accessible caused scintillations the same as on a blende screen, sensitive film was 1.5 times the size of the object.' A lignum-vitre in Nicaragua but the prejudice against but feebler (11, 26, 27, 30, 33). photograph of the radio-active diamond (17) was this material is retarding its exploitation. It is re­ 18. A blende screen was made by coating a glass taken by the light of its scintillations on the blende ported that the Government of Honduras is taking slip with very sensitive zinc sulphide. This was laid screen (17, 26, 30, 33), giving forty-eight hours' ex­ steps to introduce its wood into the market but it if' on the diamond, the ZnS side next the diamond; the posure. The three bunches of luminosity come from likely to encounter the same opposition as in the case scintillations were easily seen through it in all their the corners of the crystal that are in contact with the of the Nicaraguan WOOd. There is need for thorough characteristic appearance, with concentration at the screen. The photographic impression is certainly dis­ investigation of the properties and behavior of these edges and corners. A piece of aluminum sheet, 0.06 continuous, appearing granular-corresponding to the and other kinds of lignum-vitre with a view to their mm. thick, was moved about between the screen and granular character of the screen. It appears that the standardization and to the devising of methods of crystal of diamond, and there was no doubt what­ different grains shine and continue to shine by their treatment and manufacture which will overcome or ever that the aluminum stopped all the scintillations. own residual phosphorescent light under the impact of minimize the difficulties in their utilization. It is It was absolutely dark where tlie aluminum coveretl the a-particles. In a further experiment the diamond of much greater importance now to make some of the the crystal. was illuminated by the arc lamp, and a photograph so-called inferior grades acceptable than it is to search 19. The diamond (17) was then held in contact with was made of the diamond crystal in situ as well as of for substitutes among woods of entirely different struc­ the card back of a platinocyanide of barium screen. the screen. This gave a good image of the stone, and ture and properties. The luminous patch due to (3- or r .-rays, or to both, also of the granular surface of the screen. There is a very considerable quantity of true lignum­ was quite evident, moving about as the diamond was 28. It is certain that, in addition to a-rays, the vitre in the coastal region of Colombia and Venezuela. moved. The sheet of aluminum foil used in the former diamond (17) gives off a (lonsiderable amount of other Very little of it is now on the market, partly because experiment (0.06 mm. thick) was put between the crys­ rays (10, 19, 26, 42, 43). This is shown by the early the trade fears the substitution of "vera" or "Maracai­ tal and the back of the screen, and there was little, if experiments, where photographic images with the dia­ bo lignum-vitre" for the genuine. In 1917 a shipment any, diminution in the luminosity. It is therefore quite mond were obtained through one, two, three, and four of a few tons was received by a New York dealer from certain that the radio-active diamond gives off other sheets of aluminum foil-each 0.01 mm. thick. the Port of Colombia. The logs were 5 or 6 feet long, rays besides a-rays, and that the rays can penetrate 29. The crystal of active diamond (17), with which 4 to 15 inches in diameter, straight and well·shaped aluminum 0.06 mm. thick and the card back of the most of these experiments have been made, was exam­ and with all the sapwood trimmed off. It proved to be screen. ined crystallographically by Dr. Tutton, who reported excellent wood, approximating Cuban quality, accord­ 20. The diamond (17) was put into various fluores­ to me that the crystal is an apparent octahedron-but ing to report. cent solutions (uranine in water, Silberrard's p-nitroso­ composed of two supplementary tetrahedra showing The "Maracaibo lignum-vit,e" or vera (Bulnesia dimethyl-anilinenaphthaline compound, and quinine on three of the edges the usual grooves where the in­ arborea) is much like the genuine lignum-vitre (Guaia­ sulphate). It did not occasion the slightest fluores­ terpenetration of the tetrahedra is not complete. cum sp.) in being dense, cross-grained and resinou�. cence, although its own faint luminosity could be seen 30. Experiments show that exposure of a zinc-sul­ It is not, however, considered suitable for bearings and in the liquid. phide screen to the impact of electrons from the nega­ certain other exacting purposes, the claim being that it 21. The .active diamond (17) was cemented to a tive pole in a vacuum tube does not cause scintillations. does not wear well and that the grain is less inter­ plate of glass, and six small piilars of lead cemented It appears tliat only a-rays (positive atoms) produce woven than in the best of the genuine wood, conse­ round it the same height as the stone. The whol� this effect (11, 17, 62, 27, 33) ; it was therefore inter­ quently there is more liability to cup-shakes, radial was inverted on a sensitive film, and kept in the nar): esting to see if scintillations could be produced by cracks and similar defects. One New York dealer told for 2.25 hours. Another experiment was then tried bombarding a sulphide screen with a stream of positive the writer that 75 per cent. of the vera logs he had with the same aparatus, only altering the pOSition of atoms produced in a "Thompson" tube. An appara­ seen showed bad ring-shakes. The lower resistance to the crystal so that the lead pillars were opposite. the tus was fitted up having a :liinc-sulphide SCTeen to re­ wear may be due to the very large number of crystals angles of the crystal. The exposure in this case was ceive the positive discharge-but no effect of scintilla­ present in the wood of this genus since they would 6.5 hours. The pictures on development showen a tion could be observed. tend to act as very fine but sharp grit in bearings. strong radiation extending some distance round tht' (To be continued) The writer was unable to determine the extent to diamond (six or eight diameters) and the lead pil­ which these objections are justifiable. The fact re­ lars showed strong shadows. mains that the wood is less used now than it was a few Lignum-Vitae, the Vital Wood 22. The same experiment was repeated three times years ago and is in little demand at a price from one­ with the interposition of one, two, and three thick­ (Cfmtinued from page 5) third to one-half that of Cuban. nesses of aluminum foil 0.01 mm. thick, each was ex­ which grows in Venezuela and Colombia and bears the There is a possibility of "Paraguay lignum-vitre" or posed the same time (two hours), and all were de­ same local names. The logs are from 3 to 5 feet long "pa,lo santo," as it is known locally, entering the mar­ veloped together. Each showed strong action near the and 4 to 14 inches in diameter. The bark of the va­ ket. It grows in mixture with quebracho, which is in diamond. One thickness allowed the shadow of the rious shipments examined by the writer is of an en­ such demand for the tannin extract, and timberland lead pillars to be easily seen. Two thicknesses showed tirely different nature and appearance from that of owners are looking for an outlet for their "lignum­ the shadow with difficulty, and three thicknesses only the genuine WOOd, being rough and scaly instead of vitre." This is not the genuine wood but another showed the shape of the diamond itself. smooth with rather large flakes. It is believed that a species of Bulnesia. It has been an article of export 23. The crystal (17) was removed from its circle large amount of genuine lignum-vitre exists in Haiti, for many years but only in small quantities for the of lead pillars (21). A small cell of brass tube 0.5 but owing to its large size the natives find it too diffi­ manufacture of an essential oil, "oil of guaiac wood," inch in diameter had six slots cut in it with a file. cult to get out, since the transportation facilities in used in the manufacture of certain perfumery. The diamond was mounted in such a position that the the interior are extremely poor. three corners of the triangular surface that touched Nicaraguan lignum-vitre has been on the market for SUBSTITUTES FOR LIGNUM-VITAE. the film should come opposite three of the slots. 'l'he8e many years but there is considerable objection to its No acceptable substitute has ever been found for experiments show that the diamond is giving a·rays qualities on the part of �ertain users, especially in lignuin-vitre for stern bearings and certain other ex­ copiously. France, England, Holland and Denmark, who assert acting uses. The "mancano" of the Philippines was that it has too great a tendency to check and spIlt. urged for this purpose but has not found favor. The y-RAYS FROM THE RADIO ACTIVE DIAMOND. On the other hand it has been used with success in "varnish-tree" of India has been suggested by various 24. The diamond (17) crystal was fixed with its Japan, China, Germany and to a greater or less extent writers but is apparently unsuited. A New York deal­ sharpest point upwards in a small thick cell of brass. in the United States. The shipyards on the Pacific er informs the writer that he has been offered 100 Exactly over the point was a small hole 0.5 mm. in coast use it exclusively. It seems likely that the ob­ tons of "African lignum-vitre," but the nature of this diameter and 5mm. long. On the top was a piece of jectionable features could be overcome through im­ wood and the species of tree producing it are un­ sensitive film enclosed in black paper. The whole wal; proved methods of handling and manufacture. The known. Genuine lignum-vitre does not grow naturally kept in the dark for three hours, when a fair image largest log of available record was 36 in�hes in diam­ anywhere in the world except in tropical America, of the hole was obtained on development. The appa­ eter, 9 feet in length and weighed 4,260 pounds. Usu­ though various woods, especially in Australia, go by ratus, with another sheet of sensitive film in it, was ally the logs are from 4 to 8 feet long and from 9 to that name. . fixed between the pointed poles of a powerful electro- 24 inches through, with a good percentage over 12 During the war when the demands of the ship-build-

© 1919 SCIENTIFIC AMERICAN, INC. 16 SCIENTIFlCAMERICAN SUPPLEMENTNQ 2270 July 5, 1919

ing industry were especially heavy and genuine from the power of the transmitter; that is to say, The purpose and action of most types of detectors lignum-vitre stocks were short on account of limited whether a thousand or ten receiving stations are re­ are to act as a valve, allowing the current to pass shipping facilities, an inferior substitute, known as ceiving a message at one time, the effect on the trans­ through in one direction only, or offering what is "Panama lignum-vitre" or "yellow guayacan" was used mitter is the same. Indeed, it is never known whether known as a uni-Iateral conduction to the current. The by the Emergency Fleet Corporation. This came about one's transmitted signals are being picked up or not, action is clearly shown in the last of the remaining largely through confusion of names. The Panama unless one receives an acknowledgment. The trans­ sketches, depicting first the high-frequency current, and wood in question is locally known as "guayacan," a mitted waves spread out in all directions to be picked then the same current after passing through the name also applied to the genuine wood, although the up or not, growing weaker and weaker the farther detector. two are of entirely different families of trees and are they go away from the transmitter. A receiver which The average receiving set comprises tuning instru­ wholly unlike in structure and properties. Yellow is sufficiently sensitive may be made to intercept the ments, for varying the antenna and receiving circuit guayacan (Tabebuia sp.) seems to be lacking in the waves within the range of the transmitter. It follows so as to bring the receiving apparatus in tune with the essential properties of genuine lignum-vitre and is prob­ that the farther a receiving set is from a given trans­ desired signals, a detector, a pair of telephone receivers, ably no better suited for stern bearings than our native mitter, the more delicate it must be. That fact ex­ and the miscellaneous equipment necessary to round beech which was formerly used in a small way. plains why almost any kind of aerial--even a common out the installation. Sitting before his tuning instru­ Regarding the use of yellow guayacan, the Bureau umbrella or a short length of stove-pipe-and a crude ment, the operator can, by the mere turn of a knob or of Construction and Repair of the U. S. Navy Depart­ receiving set may be used for receiving nearby signals. two, search through the entire range of wavelengths, ment advises the writer in a letter dated March 29, picking up the various signals then passing through THE IMPORTANT MATTER OF TUNING. 1919, that it "made one purchase of Tabebuia with the space as he gets in tune with them. Indeed, that is expectation that this material would be suitable for Now all wireless waves are not alike; they have one of the greatest fascinations of radio-this matter the same uses for which the genuine lignum-vitre is different wavelength values as already indicated. of eavesdropping, so to speak, on all transmitting required. Tests have proven that this material has Wavelengths vary from 40 to 18,000 meters, the longer stations at will, while being instantly able to concen­ sufficient strength and hardness but is lacking in oil values being used in long-distance, high-power stations, trate on any one by sharp tuning. content which prohibits its use for stern bearings while the shorter wavelengths are employed by the So much for a broad introduction to the subject of which require wood of self-lubricating properties." Government, ship stations and amateurs. radio communication. In subsequent chapters the The writer was recently informed by a person fa­ This matter of wavelengths is a most important one actual installation and operation of radio equipment miliar with the timbers 6f Central America that at in radio communication. All transmitters emit signals are taken up in proper turn. least 40 different kinds of woods are locally called of varying wavelengths, and all receiving stations may "guayacan. " The experience with the Panama wood be adjusted to receive signals of any wavelength, and shows the danger lurking in that name and emphasizes hence signals from any transmitter. Thus if trans­ the need for discrimination on the part of users and mitter A is emitting signals on a wavelength of 300 SCIENTIFIC AMERICAN buyers of lignum-vitre if they would avoid being im­ meters, and transmitter B is emitting signals of 600 posed on, whether intentionally or otherwise. meters, a receiving set can be adjusted for 300 meters SUPPLEMENT to receive from A, or 600 meters to receive from B. Founded 1876 It is this matter of transmitting signals of a given Experimental Wireless Published by Scientific American Publishing Co. wavelength and picking them up at the receiving sta­ (Oontinued from page 13 ) New York, Saturday, JUly 5, 1919 tion which is known as tuning. And it is this tuning Munn & Co •• 213 Bro.d..... y.N ...... York On airplanes, dirigibles, and other aircraft in gen­ which permits several transmitters and receivers to Charles Allen Munn, President; Orson D. Munn, Treasurer eral, the antenna system consists of a trailing wire in operate in a given locality at one time, without unduly Allan C. Hoffman, Secretary. all at 233 Broad.... ay most cases. While the aircraft is in flight, a wire interfering with one another. several hundred feet in length is paid out from a reel. Indeed, the most practical example of the value of The Scientific American Publications A stream-lined weight is fastened to the free end of the tuning is offered in the regulations applying to ama­ Sclentlllc AmericanSupplement (established 1876) per year 11.00

wire, so as to keep it trailing behind the aircraft. When teur wireless in the United States, which specify that ScIent11lc American(established 1845) • • 5.00 the aircraft is about to land, the wire is taken up on amateur transmitters must be tuned to wavelengths The combined mbacrlptlon rates and rates to rorelgn countrl_. including Oanada, will be !urnl8hed upon application. the reel. In some airplanes the aerial consists of wires below 200 meters. In this manner the commercial and Remit by posta.! or express money order, bank drart or check. stretched between posts on the top wings, or between Government transmitters, operating on longer wave­ Scientific American Publishing Co. other members. In the case of at least one dirigible, lengths, can communicate with their respective receiv­ namely, the C-5 of the United States Navy, which was ing stations without interference of the shorter wave­ 233 Broadway, New York blown to sea after a successful flight to Newfound­ length transmitters. land, the aerial wires were placed inside the gasbag. In practice, tuning is not as perfect as one would The purpose of the Supplement i8 '0 publiah A live tree makes an excellent antenna for receiving. hope for. That is to say, even despite a wide differ­ the more important announcements of di8tin­ In fact, during a recent U. S. Signal Corps demonstra­ ence in tbne, one transmitter may seriously interfere guished technologists, to digest significant arti­ tion at Washington, D. C., a live tree was employed in with another. This is usually the case when one trans­ cUJs that appear in European publications, and receiving messages from powerful stations in Europe. mitter is quite close to a receiving station, while the altogether toJ reflect the most advanced thought Of course, most of these improvised aerials are only desired transmitter is some distance away. Even in 8cience and industry throughout the world. suitable for receiving purposes, because in transmitting though the receiving station is tuned for the distant it is imperative to have a good aerial in order to im­ transmitter, the signals of the nearby transmitter force part the waves to the ether in the most efficient man­ themselves on the receiver. This result 1s known as Back Numbers of the Scientific American ner. However, it must not be inferred from all that forced oscillations. Supplement has been written, so far, that one aerial is required Tuning is a matter of varying the oscillating or radio SUPPLEMENTS bearing a date earlier than Janual'J' for the transmitter and another for the receiver. If frequency of wavelength. Most transmitters, unless 1st. 1918, can be supplied by the H. W. WlllOn Oom· an aerial is of the proper design and size, it may be they are of the "fixed" variety, can be generally tuned ·pany, 958-964 University Ave., Bronx, New York, N. Y. employed for receiving and transmitting; and for this to any desired wavelength over a considerable range, Please order such back numbers from the WUson Com· purpose a switch is employed which permits of connect­ by varying the capacity and inductance in the oscillat­ pany. Supplements for January 1st, 1918, and suble­ ing either set with the aerial at will. ing and the aerial circuit, while the receiving set can quent issues can be supplied at 10 cents each by As for the so-called ground or earth connection, thi'l also be varied by varying the capacity and inductance SCIEN IFIC AMERICAN PuBLISHING Co., 233 Broadway, is merely a matfer of a good electrical connection with in the aerial and associated circuits. T New York. the ground, or a capacity effect. On shipboard the The currents induced in the receiving aerial by the problem is merely one of securing a connection with passage of signal waves are transferred to the receiv­ the metal hull, or if the ship is of the wooden design, ing circuit proper. Between the two circuits there WE wish to call attention to the fact that we are in a may be a close or loose coupling, aecording to require­ having a plate in the water. In the city, the ground position to render competent services in every branch is merely a connection with a water or gas pipe, prefer­ ments. These currents, being of the high-frequency of patent or trade-mark work. Our statr Is compoeed ably the former. In the country the ground may be a alternating current category, cannot be detected by or­ of mechanical, electrical and chemical experts, thor­ special one, prepared with little trouble. In localities dinary electrical apparatus. A telephone receiver, for oughly trained to prepare and prosecute all patent ap­ where it is next to impossible to make a good contact instance, while sensitive in the extreme and responsive plications, irrespective of the complex: nature of the with the earth, such as in sandy or rocky regions, one to weak electrical currents, will not respond to these subject matter involved, or of the specialized, technical, resorts to the capacity ground or so-called counterpoise, high-frequency currents. The reasons why a telephone or scientific knowledge required therefor. which is nothing more than an arrangement of wires receiver cannot be connected to the high-frequency We also have associates throughout the world, who laid on the ground or supported a short distance above circuit are: In the first place, the little magnet coils assist in the prosecution of patent and trade-mark ap­ the ground, arranged very much after the fashion of contained in the receiver exert a choking effect upon plications filed in all countries foreigil to the United the antenna but much lower, of course. Still another the currents of such high frequency, which effectually States. form of counterpoise is a piece of wire netting, spread blocks their passage. Low frequency and of audible MUNN &; Co., on the surface. In the case of aircraft, the ground is nature, intermittent direct currents and continuous di­ Branch Office: Patent SolWitor•• also of the capacity of counterpoise type. The wires of rect currents will readily pass, producing a sound each 625 F Street, N. W., 233 Broadway, the rigging are used to form a capacity ground. time there is any change in their value. Hence it Washington, D. C. New York, N. Y. Hence it becomes obvious that the term "ground " is a becomes necessary to convert the high-frequency al­ misleading one, particularly in cases where there is no ternating currents into some form of current that can operate the telephone receiver. ground connection at all. However, it is the accepted Table of Contents term and must therefore be abided by. Various methods are available for converting and PAGE Coming to the receiving side of wireless communica­ detecting high-frequency currents in a receiving circuit, How to Study SteeL-By Cosmos Johns ...... 2 ,Lign um-VUre, the Vital Wood.-By Samuel J. Record... 4 among these being ingenious rectifying devices, sensi­ tion, we find the situation just the reverse of the trans­ The Strongest and Most Dura·ble Fiber.-By W. Norman mitter. The currents induced in the aerial by the in­ tive modiflers which modify a telephone circuit in ac­ Boase ...... 6 tercepted radio waves flow down through the aerial cordance with the varying strength of the antenna Flower Camoullage.-Bry Francis M. Fultz ...... 8 circuit, and are transferred to the receiving circuit, currents, electric lamps of special construction knowu TowElr Clock Escapements.-By A. T. Hare ...... 10 The Physiological Sensations Produced by Detonations ... 11 where they operate certain instruments which in turn as vacuum tubes, and so on. The device that converts Experimental Wireless Telegraphy and Telephony -I.- give the operator some indication of their passage. the antenna currents so that they may be detected By Louis Gerard Pacent and Austin C. Lescl1rboura.. 12 Practically speaking, a receiver does not take away with a telephone receiver, is known as the detector. Acquired Badlo-Activity.-By Sir WIl1iam Crookes...... 14

© 1919 SCIENTIFIC AMERICAN, INC.