History of Motion Pictures

by Edward W Kellogg

First Installment History of Sound Motion Pictures by Edward W Kellogg

Our thanks to Tom Fine for finding and scanning the Kellogg paper, which we present here as a “searchable image”.

John G. (Jay) McKnight, Chair AES Historical Committee 2003 Dec 04

Copyright © 1955 SMPTE. Reprinted from the Journal of the SMPTE, 1955 June, pp 291...302; July, pp 356...374; and August, pp 422...437.

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By choosing to view this document, you agree to all provisions of the copyright laws protecting it. FIRST INSTALLMENT

History of Sound Motion Pictures By EDWARD W. KELLOGG

Excellent accounts of the history of the development of sound motion pictures special construction, to provide maxi- have been published in this Journal by Theisen6 in 1941 and by Sponablee in 1947. mum volume and long playing, the The present paper restates some of the information given in those papers, supple- cylinder record was oversize, and the menting it with some hitherto unpublished material, and discusses some of the horn and considerably larger important advances after 1930. than those of home . Be- One of the numerous omissions of topics which undeniably deserve discussion tween the reproducing stylus and the at length, is that, except for some early work, no attempt is made to cover develop- diaphragm was a mechanical power am- ments abroad. The subject of 16mm developments is discussed with a brevity plifier, apparently using the principle of altogether out-of-keeping with its importance. This has been on the theory that capstans used on shipboard. There was a basically the problems are similar to those of 35mm sound, and that whatever has continuously rotating amber cylinder brought improvement to one has been applied to both. and a hard rubber brake-shoe subtending Edison invented the motion pictures as a supplement to his , in about 130’ of arc. One end of the shoe the belief that sound plus a moving picture would provide better entertainment was connected to the reproducing stylus than sound alone. But in a short time the movies proved to be good enough enter- in such a manner that an upward dis- tainment without sound. It has been said that although the motion picture and placement of the stylus would increase the phonograph were intended to be partners, they grew up separately. And it the pressure between shoe and cylinder; might be added that the motion picture held the phonograph in such low esteem and the other end of the shoe was con- that for years it would not speak. Throughout the long history of efforts to add nected through a slender rod to the dia- sound, the success of the silent movie was the great obstacle to commercialization phragm, in such a way that the shoe of talking pictures. movement resulting from increased fric- tion would give an upward push on the diaphragm.” One may well imagine Early Sound Pictures Using blissements Gaumont” used the system that the adjustment of this device to give the Phonograph developed by Peterson and Poulsen. substantial gain without producing chat- The idea of combining recorded Laemmle. An attempt by Carl Laemmle tering must have tested the skill of the sound with the motion pictures is as old of Paramount in 1907 to exploit a best of operators. Nevertheless, it must as the motion picture itself33 (if we ex- combination of phonograph and motion have worked, for the record indicates clude the early “zoetrope” invented in picture is mentioned in Sponable’s that the Edison talking-picture show ran 1833 by W. G. In a paper, paper.6 This was a German development for several months in Keith’s Colonial “What Happened in the Beginning,” called “Synchroscope.” It was handi- Theatre in , with much ac- F. H. Richardson’ reproduced a letter in capped by the short time which the rec- claim, and was shown in other large which Thomas A. Edison quoted from ord would play, and after some appar- cities of America and in other countries. his early notes: “In the year 1887, the ently successful demonstrations, was The arrangement for synchronizing idea occurred to me that it would be pos- dropped for want of a supply of pictures was not in accordance with present prac- sible to devise an instrument which with sound to maintain programs in the tices. The phonograph behind the should do for the eye what the phono- theaters where it was tried.13 screen determined the speed, being con- graph does for the ear, and that by a nected through a string belt to a syn- combination of the two all motion and Pomerede, Amet, Bristol. Theisen’s chronizing device at the projector. The sound could be recorded and reproduced paper6 mentions combinations of phono- belt pulleys were about 3 in. in diameter. simultaneously.” The letter proceeds to graph and motion pictures using flexible The belt passed from the phonograph up tell of the development of the motion shafts or other mechanical connections, over idler pulleys and overhead, back tm picture (and is followed by letters from by Georges Pomerede2 (1907 patent), the booth. The synchronizing device , George Eastman, C. and E. H. Amet“ (1912 to 1918) who applied a brake to the projector, and the Francis Jenkins and others, related to used electrical methods for the sound. brake-shoe pressure depended on the rel- motion-picture inventions). Edison in Wm. H. BristoP began his work on ative phase of phonograph and projec- 1895 tried on the public the combination synchronous sound about 1917. tor, increasing rapidly as the projector of a phonograph with his “peep show” Siren Type of Amplijier. An ingenious got ahead in phase. With an even force moving pi~ture.~,”He built at least 50 attempt to obtain amplification in re- (and probably more) of the combination production used the movements of the I machines. phonograph needle to vary the opening I of an air-valve, connected to a source of Gaumont. Leon Gaumont, in Fran~e,~ air pressure. This device was employed began as early as 1901 to work on com- for sound pictures by Oskar Messter5*’6 bining the phonograph and motion pic- (Germany 1903-4). In , whereit ture. He worked on the project during was known as the “Auxetophone,” it had several widely separated intervals. Thei- some use for phonographs. Its invention sen6refers to a series of shows of the “ is credited by the Encyclopedia Britan- Parlant” at the Gaumont Palace in nica to Short (1898), with improve- Paris in 1913 and to demonstrations in ments by the Hon. C. A. Parsons. the . After 1926 the “Eta- Edison. In 1913 Edison made a seri- Presented on May 5, 1954, at the Society’s ous effort to provide synchronized Convention at Washington, D.C., by Edward phonograph sound. The equipment is on W. Kellogg, Consulting Engineer, 276 Merion Ave., Haddonfield, N.J. exhibit at the Edison Museum in West Fig. 1. Mechanical power of (This paper was received on October 25, 1954.) Orange, N.J. The phonograph is of Thomas A. Edison and Daniel Higham.

June 1955 Journal of the SMPTE Volume 64 291 (No Model J 3 Sheeta-Sheet I beam of modulated light, and uses a A. 0. & C. A. BELL & S. TAINTER. light-sensitive device (selenium cells) to TRANSMITTINO AND RECORDINO BY BADIANT ENEBBY. detect the received fluctuations, thus anticipating the essential principle of the 341.213. Patented Mav 4. 1886.- No. reproducing system which was used in many later experiments. Blake. Prof. E. W. Blake of Brown University in 1878 made photographic recordsof speech sounds on a moving pho- tographic plate, using a vibrating mirror. 6,18 FrittS. U.S. Patent No. 1,203,190, filed in 1880 by Charles E. FriLts,S,6 discloses photographic soundtracks and a great variety of devices for recording and reproducing, but there does not appear to be evidence of much significant ex- perimental work. Bell and Tainter. In the Smithsonian Museum in Washington, D.C., are a 0 number of large glass disks carrying spiral n sound tracks. These were made by a Liib. 2. \\ “..- method described in U.S. Patent No. 341,213 (filed 1885) to Alexander Gra- ie 2rcr Sensitized ham Bell, Chichester A. Bell and Sumner 11 / Disk (in Box) Tainter. Light from a steady source was transmitted in a relatively narrow beam through a piece of stationary glass, and then further restricted by a slit where it reached the circular photographic plate. Just above the place where the light entered the stationary glass, a tiny jet of ink (or other light-absorbing liquid) was directed against the surface. The nozzle was attached to a “sounding board” (small plate) which picked up the sound . The jiggles of the nozzle caused in the stream of ink which flowed down over the surface, and these modulated the transmitted light. Fig. 2. Variable density recording system of A. G. Bell, C. A. Bell and Sumner Some years ago it became desirable, in Tainter, 1886. connection with a patent suit, to demon- strate that the spiral track was really a soundtrack. Contact prints (on celluloid on the projector crank, normal phase tation toward photographic recording, ) were made of several of the most relation was maintained. The projec- nor even that ultimate application to promising looking of the glass plates, and tionist watched for synchronism and synchronous sound for motion pictures a reproducing system arranged, giving had a slight degree of control by turning was (in many cases) a main objective. the record the benefit of modern equip- the crank harder if the picture was behind It was rather that photographic recording ment in this respect. The approximate or easing it off if it was ahead. represented a new medium, which best speed was found by trial. (The So far as I have learned, there were seemed to offer promise of much superior original recording machine was hand- few further efforts (at least in the U.S.1 results. A mechanical system seems in- cranked). The photographic image to provide sound for pictures by means herently crude where such delicacy is had suffered from age and was very of phonograph (mechanical) recording needed as in reproducing sound; in noisy, and the total recording lasted until the Warner Brothers’ contrast to which recording by a beam of only a few seconds. But it was with some- system of 1926. light would seem ideal. The experi- thing of the thrill of an antiquarian that menters have all been conscious of the we listened to the voice from the past. Photographic Sound Recording handicap imposed by the necessity of “This is . . . . I am. . . in the . . . labora- A history of sound pictures necessarily making ponderable mechanical parts tory.” The date was given too ‘‘ . . . , includes the many efforts to record sound vibrate at high frequency. eighteen eight- . . .?” photographically, whether or not the ex- So we find that efforts to record sound perimenters made any attempt to com- photographically began before there Others. Sponable’s historical paper bine the sound with pictures, or were even were such things as motion pictures on mentions numerous other workers and interested in that application. Despite strips of film. Before the invention of the their patents. Several of these modulated the obvious advantages, from the syn- , , the light by means of a small mirror chronized-sound standpoint, of a photo- interested in aiding the deaf, had made connected to a diaphragm so that vibra- graphic record of the sound on the same photographic records of “manometric tion caused rotation, thus anticipating film with the picture, it does not appear flames,” showing voice waves. His pat- features of equipment used by C. A. that this.consideration was necessarily an ent, No. 235,199, filed in 1880, shows a Hoxie in the work at important factor in directing experimen- system for transmitting speech over a Co. Of the developments which, although

292 June 1955 Journal of the SMPTE Volume 64 not leading to any commercial system, strong , was invented by sities before saturation, making it pos- deserve special mention, I shall speak of Blonde1 in 1891 and improved in 1893 by sible to produce intense fields which make several inventions or discoveries which Duddell, who put it into practically for sensitivity and damping in devices of laid foundations for later developments, the form still used. It has played a vital the moving conductor type. and of the direct contributions to photo- part in photographic sound recording. Important for the reduction of cost graphic recording of Ruhmer, Lauste, de and weight of magnetic devices was the Magnetic Recording. The invention by Forest, Reis and Tykociner. discovery by the Japanese physicist T. Poulsen of Copenhagen in 1900 of re- Mishima of the properties of certain alu- cording magnetically on a steel laid Basic Inventions and Discoveries minum-nickel-cobalt alloys for perma- the foundation for modern tape record- Selenium Cells. For many years, re- nent ,3O and subsequent improve- ing, which has almost revolutionized production from photographic-sound rec- ments. ords was made possible by the selenium methods of making original record- cell. The photoconductive properties of ings.27 Improvements in Vacuum Tubes and selenium were discovered by Willoughby Auditorium . The modern Phototubes. In any list of the advances Smith in 1873, and a practical selenium of room acoustics and acoustic which contributed in an important way cell was made by Werner Siemens in treatment dates from the work of Prof. to the technical attainments in modern 1876.19The response of a selenium cell to Wallace C. Sabine of Harvard in the sound reproduction, several improve- changes in illumination is sluggish, mak- years 1895 to 1900.28 With little other ments in amplifier tubes deserve an im- ing it a very imperfect tool for sound re- equipment than a whistle, a stop portant place. Among these are : production, whereas the photoemissive and brains, he worked out the acoustic (1) The Wehneldt (oxide coated] effect on which photocells depend is principles on which successful sound re- and other low-temperature practically instantaneous, but the elec- cording and reproduction so largely emitters, which in turn made indirectly trical output from a selenium cell is very depend. heated unipotential possible. much greater. (2) The screen-grid tube. Gas-Filled Incandescent Lamps. Beyond a (3) The . The Photocell. The first indication of certain point, optical-recording systems (4) Remote cutoff or exponential photoemission was discovered by Hertz in cannot give increased exposure by in- tubes, and other variable gain tubes. 1887 and later studied by Hallwachs creasing the size of the source, but only by (5) The phototube with its (1888), Stoletow (1890) and Elster and increasing the intensity (candles per high sensitivity to infrared light. Geitel (1889 to 1913).19J0Although by square centimeter), which means higher (6) The gas-filled phototube with its 1900 much had been learned, practical temperature. Early incandescent lamps increased output. photocells did not become generally were well exhausted because all gas re- available till some years later, nor were sults in loss of heat by convection and Early Work on Sound on they of help toward sound reproduction hence lowered efficiency. In 1911-13 Motion-Picture Film without electronic .2!J2 Irving Langmuir of General Electric Co. Ruhmer. Ernst Ruhmer in Berlin5~6~31in studied the effects of inert gas not only on 1901 began publication of the results of Thermal Emission - The “Edison heat loss, but also on the rate of evapora- his work on photographic sound record- Efect.” Edison discovered in 1883 that a tion of tungsten from the filament surface, ing, which extended over a period of small current could flow through evacu- which is the factor which determines about twelve years. As sources of modu- ated space in a lamp bulb, between a permissible operating temperature. He lated light he superimposed voice currents hot filament and a separate electrode. showed that such gases as nitrogen, or on the continuous currents in electric The Fleming “Valve,” invented in 1905, better yet argon (the heavier the better), arcs. He used considerably higher film made use of this principle, played an im- at pressures well up toward atmospheric speeds than those used for pictures. portant part in early wireless telegraphy or even higher, could with suitably formed Sponable reported (ref. 6, p. 278) that and was the forerunner of thermionic filaments so retard the evaporation of some of Riihmer’s Photographophon amplifiers.26 tungsten that the higher permissible films were brought to this country by the The . The invention of the temperature much more than compen- Corp., and that the articula- “Audion” by in 1907 sated for the added heat convection, tion was clear; also, this reference shows marked the beginning of the electronic thus giving several-fold increase in effi- a sample of Ruhmer’s soundtrack. A era. As has been emphasized by many cency as well as whiter light. With the variable-area track by Rtihmer is shown writers, it was the electronic amplifier gas, the evaporated tungsten is carried to in the Theisen history (ref. 5, p. 421), the which unlocked the door to progress and the top of the bulb instead of blacken- Scient8c American of 19Ol3lbeing cited as improvement in almost every phase of ing the sides, in the optical path.29 reference. Presumably Ruhmer experi- mented with both systems. sound transmission, recording and re- Magnetic Materials. The development production. However, amplifying tubes of several alloys of iron, nickel and cobalt Lauste. This Society has taken special did not become generally available to having extraordinary magnetic proper- note of the work of Eugene Augustine experimenters for over a decade. The ties is reported by H. D. Arnold and G. Lauste, in a 1931 report of the Historical de Forest patent2? (acquired by the W. Elmen in the Technical Committee,32 in a paper by Merritt Telephone Company) was basic and un- Journal of July 1923, and by Elmen in the Crawf~rd~~and in placing his name on challenged, but the vacuum techniques January 1929 and July 1929 issues. The the Society’s Honor Roll. The young of some of the foremost laboratories of extremely high permeability and low Frenchman joined the staff of Thomas A. the countryN were needed to make of hysteresis of Permalloy have .made it Edison in 1887, where he did construc- the audion a dependable and reasonably possible to greatly reduce in tion and experimental work till 1892. rugged tool. * and in many electrome- For two years he worked on another The Oscillograph. The oscillograph, chanical devices, and to provide more project and then, in association with consisting of a small mirror mounted on a successful magnetic shielding than would Maj. Latham, developed a projector pair of conductors, close together, in a otherwise be possible. In another alloy which was the first to incorporate the which has been called Perminvar, con- extra sprocket and free loops with the * Much higher vacuum than de Forest had been stancy of permeability and low hysteresis intermittent. Lauste’s interest in photo- able to obtain was necessary. This was inde- (making for low distortion) have been pendently accomplished by I. Langmuir of graphic sound recording was first General Electric Co. and H. D. Arnold of carried still farther. Another alloy named aroused when in 1888 he found in an old C0.24 Permendur can carry very high flux den- copy of the Scientijc American (May 21,

Kellogg: History of Sound Motion Pictures 293 1881) an account of Dr. Bell’s experiment cell. The light from the mercury arc is reflections on the applications and future in transmitting sound over a modulated particularly potent photographically, but of sound motion pictures. light-beam, and converting to electrical is sluggish in following the input modula- The man whose invention gave us by means of a selenium cell. tion, which results in some loss of the amplifiers in which the heaviest object This suggested the thought of recording higher audio frequencies. that had to be moved was an , the sound photographically on the same surely had a right to wish to do away strip with the picture. It was not till Foreign Developments Which Led with moving mechanical parts in micro- about 1900 that he began to find oppor- to Commercial Systems phones, light-modulators and loud- tunity to work on this project. He Tri-Ergon (meaning “the work of three”). speakers. For he experi- worked for several years in the United Josef Engl, Joseph Massole and Hans mented with the conductivity of gas States and then went to England where Vogt, in Germany, began in 1918 flames and of open arcs as affected by he pursued his experiments. A British the development of a system of sound sound waves, and with fine platinum patent (No. 18,057, filed in 1906) shows a pictures which later was commercial- heated to a dull red by a direct well thought-out system. Lauste re- ized under the name Tonbild Syndicat current and subjected to the cooling ceived some financial backing in 1908 AG (abbreviated to T~bis).~J~They effect of the air vibrations superimposed from the manager of the Cine- used a modulated glow discharge for on a slight continuous air movement. matograph Co. recording, and a photocell for repro- The changes in resistance of the wires To modulate the recording light, ducing. Of chief concern in this country with variations of temperature gave Lauste used rocking mirrors and what were the Tri-Ergon patents,36 in which rise to telephonic currents. have been described as “grate-type numerous claims allowed by the U.S. For light modulators he tried “the light-valves.” The mirror system was Patent Office were so broad that had speaking flame” (probably the “mano- too sensitive to camera vibrations, and their validity been sustained they would metric” flame of Konig) and a tiny the grate-type valves which he was able have almost swamped the industry. incandescent lamp, carrying voice cur- to build had too much inertia. In 1910 In particular, one patent (1,713,726) rents superimposed on direct current. he began working with modulators of which claimed the use of a flywheel on The lamp was designed to have very the string galvanometer type, with ex- the shaft of a roller or sprocket which rapid filament cooling (partly by using cellent results. The historical account carries the film past the translation a short filament, so that heat conduction by Theisen,6 shows photographs of some point, to take out speed variations, was to the lead-in wires would be high). of Lauste’s apparatus. He spent some the basis of prolonged litigation, being On listening to these sources by means of time with Ernst Ruhmer in , a finally declared invalid by the U.S. a photocell and amplifier, de Forest stimulating and profitable association. Supreme Court (l935).ll4 But in the was convinced that they gave excep- He visited America in 1911 and as part of meantime the efforts to avoid what tional quality (even compared with his demonstration made what was prob- were thought to be dangerous in- the condenser ), but they ably the first actual sound-on-film fringements of the Tri-Ergon flywheel proved entirely inadequate for making motion picture made in the U.S. A neces- claims, had for seven years steered a useful soundtrack giving very small per- sary return to England, shortage of capi- the course of mechanical designs on the centage of modulation and probably also tal, and the war, halted Lauste’s sound- part of the major equipment manu- underexposure. Finally a successful picture researches. In his paper on facturers into inferior or more com- source of modulated light for recording Lauste, Crawford expresses the thought plicated constructions. (See section on was found in a gas-filled tube excited that had it not been for this unfortunate Mechanical Systems.) by modulated high-frequency currents interruption, plus very limited resources, In Germany the Tri-Ergon patents from a 5- to 10-w telephone trans- and had electronic amplifiers been avail- controlled the situation. The large mitter. This was named the “Photion.” able to Lauste, commercialization of picture producing companies, U.F.A. and A slit, 1; to 2 mils wide and 3/32 in. sound pictures might well have gotten Klangfilm (a subsidiary of Siemens & long, adjacent to the film, was used to started a decade before it actually did. Halske and A.E.G.), took licenses under restrict the size of the exposing beam. E. E. Ries filed application in 1913 for the Tri-Ergon patents. A brief account A similar slit was used in reproduction. a patent (No. 1,473,976, issued in 1923) of the patent negotiations and agree- Both potassium photocells and Case in which broad claims were allowed on ments in this company and in Germany Thalofide3’*” cells were used in repro- the essentials of a single-film system. will be found in the Sponable paper.6 ducing equipment, the greater sensi- The patent became the basis of later Peterson and Poulsen in Denmark de- tivity obtainable with the Thalofide litigation.B veloped a system (1923) which was com- cell being a consideration offsetting the mercialized in Germany under the faster response of the photocell. The Tykociner. In 1918 and following, name Tonfilm.6 They used an oscillo- design and construction of amplifiers Prof. J. T. Tykociner of the University of graph as the recording light modulator using his Audion were of course very Illinois carried on experiments and de- (giving a variable-area soundtrack), familiar to de Forest. veloped a system. This work was de- and a selenium cell for reproduction. Lament is expressed that scribed before the American Institute of (One of the Tri-Ergon U.S. patents35 depending on some principles other Electrical Engineers and in the SMPE claimed the use of a photocell for this than diaphragms and horns were not Transactions.34 After pointing out that purpose, and it is likely that a German to be had, but after some discourage- three new tools had in comparatively patent accounts for the use of a se- ments with “talking arcs” and sound recent times become available for the lenium cell by Poulsen and Peterson.) radiators on the thermophone prin- solution of the sound-picture problem, This system was used by Gaumont in ciple, the commercially available horn (namely, high-frequency currents, pho- France and by British Acoustic Films, and diaphragm speakers were accepted toelectricity, and thermionic amplifiers), Ltd. as the only solution at the time.* Prof. Tykociner gives a broad discussion Practical models of recording and re- of requirements and possible arrange- The de Forest producing equipment were built, and re- ments. As a source of modulated light he Dr. de Forest tells the story of this * It is of interest that in the early part of our used for the most part a mercury arc work in the 1923 Transactions.36 The ac- investigation which led to the direct radiator with either modulated continuous cur- count is particularly interesting because dynamic speaker (Trans. AIEE, 1925, p. 461) rent or modulated high-frequency cur- he tells much of his viewpoint as he Chester W. Rice and I tried talking arcs and thermophones, and also a corona discharge rent, and for reproduction a Kunz started, and then, after describing the device - all of which avoid mechanical moving (cathode of potassium on ) photo- system which he had evolved, gives his parts - but none of these appeared pr0mising.a

294 June 1955 Journal of the SMPTE Volume 64 cordings made, using principally a com- quency range, and loudspeakers that The Aeo-light was mounted in a tube bined camera and recorder, and many gave unnatural voices, and perhaps too, which entered the camera at the back. demonstrations given. demonstration films that were uninter- Directly against the film was a light- The de Forest pape9 reviewed earlier esting) contributed to loss of the im- restricting slit made by silvering a thin history of efforts to record sound photo- pressiveness needed for doing business. quartz plate, ruling a slit 0.0006 in. graphically, and gave appreciative ac- Several years later the “de Forest wide in the silver, and cementing over knowledgment of the help that had been Phonofilm Co.” was bought by Schles- it a thin piece of glass which was given by Theodore W. Case.37 inger of London and South Africa. then lapped to a thickness of about To have guessed wrong on some sub- 0.001 in. The slit was thus protected ject is no reflection on the insight of an Work at the Theodore W. Case from collecting dirt from the film. The experimenter, but several instances are Laboratory ( Movietone)6 end of the Aeo-light, where the glow was striking, in the light of later develop- Theodore W. Cases7 became inter- concentrated, was close behind the ments. Speaking of the efforts to pro- ested in modulating light and deriving slit. A Bell & Howell contact printer vide sound by means of the phono- telephonic currents from it in 1911, was modified to make possible the in- graph, the author said: “The funda- while a student at Yale. In 1914 he dependent printing of picture and sound. mental difficulties involved in this organized his laboratory at Auburn, Up to the fall of 1925, when the work- method were so basic that it should have ing arrangement with de Forest was I N.Y., devoting special attention to been evident from their inception, that the study of materials whose resistance terminated, the Case laboratory efforts commercial success could hardly be is altered by light, of which selenium was were directed largely to recording achieved in that direction.” (Consider the best known example. These studies principles and apparatus. It was decided the Warned Vitaphone.) Speaking of resulted (1917) in the development of then to work on a system independently loudspeakers, after saying that the loud- the Thalofide cell, in which the photo- of de Forest, and one of the next proj- speaker has been developed “to a high sensitive material is thallium oxysulfide.40 ects was to build reproducing equip- state of perfection” but left much to be These cells, which are especially sen- ment in the form of an attachment desired, he said: “I am convinced that sitive in the near infrared range, were which could be used with existing pic- final perfection will come not through widely used in Navy communication ture projectors. It was in this design any refinements of the telephone and systems during World War I. Case was that the decision was reached to place diaphragm, but by application of en- joined in 1916 by E. I. Sponable. the soundhead under the projector, tirely different principles.” (Yet phe- Experiments were continued with the and the offset of 20 frames or 144 in. nomenal improvements were made with help of an Audion amplifier obtained between picture and sound was estab- the identical elements, through refine- from de Forest. One of Case’s postwar lished. The speed of 90 ft/min was adopted for the Case system. In the ments.) developments was the barium photo- In speaking of the future of sound electric cell. first projector attachment a light-re- stricting slit was used similar to the pictures, Dr. de Forest gave a definite In 1922 attention was turned seriously “No” to the question whether the existing to sound pictures. Manometric* flames one used in the camera, but later a type of silent drama could be improved (oxyacetylene) were tried as a possible straight tungsten filament was imaged by the addition of voice. But he foresaw source of modulated light. Soon after- on the film, and in a still later model, the evolution of an entirely new type of ward Case found that the light from an a concentrated straight-axis helical fila- dramatic scheme and presentation, tak- argon arc in one of the tubes that had ment was imaged on a slit which was in turn imaged on the film. ing advantage of the freedom which had been used for infrared signalling could been such an asset to the silent moving be readily modulated and was photo- With the essential elements of a sound- on-film system developed, Case and picture (as contrasted with the stage) graphically potent. These tubes had but using sound and voice where these oxide-coated hot cathodes. A tube for Sponable began study of the patent could be effective. He also had visions recording, based on this principle, was situation, with a view to obtaining of great utility for travel films, , developed and named the Ae~-light.~*~llicenses, if necessary, for the commercial records of notable persons, and educa- It operated at between 200 and 400 v. use of their system. There appeared to be no very strong patents to interfere, tional films. was substituted for argon in The work just described was done 1922, with benefit to the actinic power except those on the use of thermionic from 1918 to 1922. About a year and a and also to the speed with which the amplifiers. A contract between General half laterse Dr. de Forest gave a brief light followed the current variation. Electric, Westinghouse and Radio-Cor- poration on the one hand and Western account of progress, reporting improve- The commercial Aeo-lights were rated Electric Co. on the other, was in effect, ments in many details, better articula- at 350 v. tion, thirty theaters equipped, much From 1922 to 1925 Case cooperated specifying the fields of activity in which each might use amplifiers, but, interest on the part of operators, films with de Forest, furnishing numerous if made of a number of celebrities and items of experimental equipment. I have not misinterpreted the account in Sponable’s historical paper, sound- contracts with leading chain exhibitors. Several sound cameras were built Again the opinion was expressed that under the direction of Sponable, in pictures had not been specifically men- the talking picture would not ever take 1922, 1923 and 1924. The 1924 model tioned, and there was some question as to the right to license use in the Case the place of the silent drama. was a modified Bell & Howell camera The Phonofilm system was used in rebuilt to Sponable’s specifications by system, the eventual decision being numerous theaters, with sound films the Bell & Howell Co. The film motion that both groups had rights. The Bell made under Dr. de Forest’s direction; in this and other cameras was unaccept- Telephone Laboratories were interested but he did not succeed in interesting the able until they had been reworked for themselves in developing sound pictures, established American picture producers. greater mechanical precision. In the and so were not immediately ready to Perhaps the industry was prospering too final designs of sound camera the sprocket license what would be a competing sys- well at the time, but judging from the was driven through a mechanical filter, tem. However their engineers were initial coolness of film executives to consisting of damped springs and a much interested in the performance the technically greatly improved systems flywheel on the sprocket shaft. The attained, and there was some thought of combining efforts. There were dem- a few years later, it is easy to imagine sound was recorded on the sprocket. that numerous imperfections which un- onstrations of both systems, but no doubtedly existed (as, for example, *A gas jet so arranged that sound vibrations plan to merge them was reached. The defective film-motion, limited fre- produce changes in the gas supplied to the jet. experience of Case and Sponable at

Kellogg: History of Sound Motion Pictures 295 General Electric Co. was rather similar. undertaking of a full-scale project for de- cording and the phonograph. The story In 1926 demonstrations were made to veloping systems of sound for motion of this development was told in 1926 to representatives of the Fox Film Corp., pictures. Craft was assistant chief engi- the American Institute of Electrical En- who became greatly interested, and neer of the Western Electric Co. from gineers.49 The recording system made finally to . After thorough 1918 to 1922, when he became chief en- use of a magnetically driven cutter so testing on their own premises, the Fox gineer. With the transfer in 1924 of re- designed that with constant current in- Film Corp. purchased rights to the Case search activities to the newly organized put, the vibratory velocity of the cutting developments (July 23, 1926), leaving Bell Telephone Laboratories, Craft was stylus was substantially constant from the question of amplifier rights to be made executive vice-president, and con- about 200 to 5000 cycles, while from 50 worked out later. The Fox-Case Corp. tinued to guide acti~ities.4~ to 200 cycles the was con- was organized to exploit the system, Whether or not there was a definite stant, a characteristic practically neces- which was given the name Movietone. policy of not putting all of the eggs in one sary to avoid overcutting by the low Courtland Smith, who had been with the basket, work on both systems was stepped notes. Two features of the design were of Fox Film Corp. and had been instru- up at about the same time (1922) and special interest: (1) the separation of the mental in bringing about the purchase, pushed with equal vigor. total mass that must be driven into three was made president of the Fox-Case The two systems had identical re- parts (armature, stylus-bar and coupling Corp. The Movietone service was quirements with respect to many ele- disk), connected together through por- established. ments, but, in particular, microphones, tions of shaft whose torsional flexibility Sponable left the Case organization to amplifiers and loudspeakers. The West- was carefully calculated to make of the give his services to the new company, one ern Electric Co. had acquired rights to structure a mechanical low-pass filter of of the first of his activities being the de- de Forest’s Audion in 1913 and made calculable mechanical impedance; and sign of recording studios in New York and great improvements in it during the next (2) a mechanical resistance consisting of later in Hollywood. In 1927 he de- few years, building up wide experience a thick-walled rubber tube (which may veloped a screen which transmitted in its applications and circuitry. be thought of as practically a rod of soft sound freely, permitting loudspeakers to Second only to electronic amplifiers in rubber) subjected at one end through the be located directly behind the picture. importance for the development of high- coupling disk to torsional vibrations. The first public showing of Movietone re- quality recording and reproducing sys- The propagation of torsional waves in cordings was in January 1927. tems was a microphone of uniform re- such a soft rubber rod is so slow that in a The Fox-Case Corp. obtained license sponse and with low distortion. With length of about 6 in. there would be to use amplifiers, first in 1926 through the amplifiers available Dr. E. C. Wente43 many wavelengths for all but the lowest Western Electric Co. and the Vitaphone was able largely to ignore the question of frequencies. Corp., and the next year revised con- output level, and to develop by 1916 a Vibrations imparted to the rubber tracts were made with Electrical Re- microphone of the condenser type, hav- reach the far end very much attenuated, search Products, Inc. (ERPI), which was ing extraordinarily and free- are reflected, and propagated back to- formed in January 1927 to handle the dom from distortion and n0ise.4~~7 ward the start, but are of neligible magni- sound-picture business for the Western In the field, the company tude when they reach it. Under such con- Electric and Telephone companies. had had considerable experience and had ditions the rubber line acts as a nearly In the Movietone reproducing system, developed units for public address work. pure mechanical resistance to load the Western Electric amplifiers and loud- The public address installations had af- filter, and, if properly matched to the fil- speakers were used. The years 1928 and forded experience with auditoriums and ter impedance, results in practically com- 1929 were marked by rapid expansion in requirements for intelligibility, while plete (and therefore uniform) transmis- facilities and personnel, successful show- experience in acoustics for sound pickup sion through the filter structure, through- ings and stepped-up schedules of news- had been gained in radio broadcasting. out the frequency band below the filter reel releases. In March 1929 the making With respect to the recording itself cutoff. The features just described are, I of silent pictures by Fox was discon- and reproduction, I shall separate the believe, the inventions of H. C. Harrison. tinued. Six months later the Fox and two stories of the disk and photographic The great improvement in records which Hearst services were united. systems. electrical recording brought, is well The British was or- known to all of us. The Disk ganized in 1929. In 1930 William Fox System Without a better reproducing system sold his interests in Fox Film and Fox In 1946 there was published a history than the phonographs of the types in use Theatres. of sound recording in the laboratories of about 1920, the improvements in the As the Fox Film Corp. was already an the Western Electric c0.4~Since the records would have been largely lost, so ERPI licensee, and therefore had rights transmission of speech was the main there was developed a greatly improved to use other Western Electric develop- business of the Telephone Co., a pro- (nonelectrical) phonograph called the ments, the Western valve gram of studying every aspect of speech Orthophonic (also largely the outcome of was adopted for the Movietone service waves was initiated about 1912, and as H. C. Harrison’s approach to the prob- (as well as for Fox studio recording), dis- part of this project, efforts were directed lem). However this part of the program placing the Aeo-light. to recording the sound. The interest had no direct bearing on the talking- soon spread to include music. In connec- picture project. In early 1925 the Colum- Work at Western Electric Co. and tion with work with disk records, Cran- bia and Victor Companies took licenses Bell Telephone Laboratories dall and Kranz built an electromagnetic from Western Electric Co. to use the re- The Western Electric Co. brought to a reproducer in 1913. In 1915 H. D. cording methods and apparatus, and to commercial stage almost simultaneously Arnold suggested that the improvement build phonographs of the Orthophonic a sound motion-picture system based on of disk recording be undertaken, using type. disk records, and one based on sound on the then available electrical equipment Sou&-on-Disk Synchronized With Pic- film. Various developments which laid (which included amplifiers). By this tures. Little time was lost in trying and the foundations for these systems had time the electrical reproducer had been demonstrating synchronized sound and been taking place through a number of improved. pictures using the new electrically re- years. The citation of the life and work The war interrupted these projects, corded disks. Craft arranged for a dem- of Edward B. Craft in this Journal4 indi- but they were resumed soon after its onstration at Yale University in 1922 and cates that his interest and enthusiasm close. A group under J. P. Maxfield another in February 1924, the equipment were in large measure responsible for the undertook the improvement of wax re- and many details of the system having

296 June 1955 Journal of the SMPTE Volume 64 been developed and improved in the the moving-coil type was developed by duction of The Singer with A1 Jolson, interval. Wente and Thurass7 which met the re- was begun in the spring of 1927 and it To provide sound for pictures, using quirements for quality, efficiency and was shown in New York on October 6. the disk-record system,5oit was necessary power-handling capabilities. Speakers Its success was such that the industry was to have records which would play con- of this design rapidly superseded those of convinced “overnight” that the day of tinuously for at least the projection time earlier design, and continued in use for sound pictures had arrived. of a 1000-ft reel (about 11 min), to plan years. a synchronous drive, and to use electrical According to the account of Lovette Improvements in the Disk System. Un- reproduction in order that, with the help and Watkin~~~the sound-on-film system, der the title “Recent Advances in of amplifiers, adequate sound output on which another group of engineers had Wax Recording”5o H. A. Frederick tells could be had. been engaged, was capable in 1924 of of a number of advances subsequent to I It was not desirable (in view of back- matching the quality of the disk system, the 1926 account by Maxfield and ground noise) with record materials then but the latter represented an older art in Harrison. By improvements in record available, materially to reduce ampli- which there were fewer uncertainties. material and wax processing techniques. tudes of cuts, and so groove pitch had to The greater confidence with which the it had been possible to reduce surface be kept nearly the same as then in current company could offer the disk system, noise by 3 to 6 db. A new pickup (4A) is use (about 100 grooves per inch). To and with which a potential customer described with smoother response and maintain quality the minimum linear would consider it, were responsible for good to about 4500 cycles, as compared groove velocity must not be reduced. choosing it as the first to be pushed. with 4000 cycles for the previous model. With a given groove pitch and minimum However, interest on the part of most of A response curve for the commercial re- velocity, the maximum playing time for the picture producers was cool, nor did corder shows practically uniform response a given record diameter is obtained by Craft, conscious of the numerous failures to 5500 cycles. Laboratory models of re- recording to half the maximum diame- of previous efforts by others, think it de- corder and reproducer are mentioned as ter, and the required playing time deter- sirable to hasten the commercialization carrying the response to 7500 cycles. The mines the needed size and corresponding of either system until its weaknesses were new recorder used a longer rubber damp- rotation speed. While the engineers worked out. ing line. Frederick gives the groove pitch could take some leeway, the choice of 16 as 10 mils and the minimum groove ve- in. outside diameter and 334 rpm, ap- Samuel Warner and Vitafihone.58 With locity as 70 ft/min. He also reported very proximately met the conditions indi- many details omitted, the foregoing is satisfactory results with re-recording. cated. the description of the sound-on-disk sys- For synchronous recording, the cam- tem which became known as Vita- Western Electric Sound on Film era and the recording turntable can be phone. Col. Nathan Levin~on,~~then Mention has been made of funda- driven by selsyn motors, which driving serving the Western Electric Co. in the mental studies of speech waves, begun in system gives the equivalent of both being Pacific district where he had had close 1912 and carried on through several geared together and driven from one association with Samuel L. Warner, years until interrupted by the war. shaft. Starting marks on both film and made a business trip to New York early Amplifier tubes became available as disk are of course essential. in 1925 and saw- a demonstration of the laboratory tools in 1913. Photographic For reproducing, the turntable and sound pictures. He felt sure that Mr. records of speech waveshapes were made, projector were mechanically geared to- Warner would be interested, and ar- using at first a carbon transmitter, an gether. A simple magnetic pickup, if not ranged for a demonstration at the first amplifier and a Duddell oscillograph. damped, has a high-frequency opportunity. Samuel Warner was more The weakest link in this chain of equip- in which the armature whips, giving ex- than convinced, and his enthusiasm ment was the transmitter, whose response cessive output and high mechanical im- quickly spread to his brothers. More varied greatly with frequency and which pedance at the needle tip.51 The mag- thorough tests were arranged, using had a high level of background noise, netic pickup used in the sound-picture cameramen, technicians and artists of making it difficult to get reliable traces of system was designed for use with replace- the Warner staff, in cooperation with consonants and other relatively weak able steel needles and damped by en- Western Electric engineers. The adop- speech sounds. The development of a closing the moving elements (except the tion of sound by a large picture-produc- better transmitter was one of the first needle-holder and needle) in oil.52 ing company would mean a huge outlay, undertakings of Edward C. Wente,43who The turntable driving systems52-54 and its success was a question not only of came to the company in 1914.4-47 evolved for the sound pictures are dis- technical performance, but of the artistic, cussed in the section on “Mechanical dramatic and psychological results which The Condenser Transmitter. If the charge Systems” - the great problem being (as could be achieved through the addition on a pair of condenser plates is main- had been the case throughout the history of sound. The tests were convincing to tained through a sufficiently high re- of sound recording) to obtain sufficiently the Warner Brothers, if not to the execu- sistance, the voltage is directly propor- nearly constant speed. tives of some other picture companies tional to the separation of the plates, SO The loudspeakers which had been de- who witnessed them. To develop and that a transmitter based on this principle veloped for public address applications55 market sound motion pictures and is an amplitude-sensitive device. If the were of the “balanced armature” type, equipment, the Vitaphone Corporation diaphragm, which is one of the condenser had good power-handling capacity, and was organized in April 1926, with plates, is so stiff in relation to its mass that were regarded as fairly satisfactory from Samuel L. Warner as its president. resonance occurs above the required fre- the standpoint of articulation. Designs of The first major Vitaphone sound pic- quency range, the diaphragm deflection is horns had been evolved which fairly suc- ture to be released was Don Juan,1@ proportional to the instantaneous air pres- cessfully controlled the directivity for (August 1926) in which music by the sure. Wente met this mechanical require- auditorium purposes. In 1923 Dr. Wente New York Philharmonic Orchestra was ment by using a stretched steel dia- built a speaker of the moving-coil type featured. The new loudspeaker de- phragm 0.002 in. thick and spaced 0.001 which gave greatly improved quality56 veloped by Wente and Thuras was ready in. from a relatively massive backplate. (especially the better bass response which in time for this. Preparations were made The very thin layer of air contributes is possible with the moving-coil drive), for producing sound pictures in Holly- greatly to the stiffness of the diaphragm, but in terms of efficiency and power- wood, where sound stages were erected but the flow of air through the narrow handling capacity it was not satisfactory. embodying the recommendations of the space toward and from a relief space It was not until 1926 that a speaker of foremost experts in acoustics. The pro- around the edges causes damping, so

Kellogg: History of Sound Motion Pictures 297 In 1928 MacKenzie described the light-valve model in use at the time, and recording and processing practice (ex- posure ranges and developments) as worked out at the Bell Telephone Labo- ratories.‘j4 The valve is mounted with the slit between ribbons horizontal - so that its image on the film is transverse to the film. The ribbons are in a strong Fig. 3. Light-valve ribbon and pole magnetic field and currents in the two are piece arrangement; section at right in opposite directions, so that they are angles to ribbons. deflected (edgewise) to increase or de- crease their separation depending on the direction of the current. The width of the that a nearly flat (uniform) response was grating formed on another grating to slit with no current in the ribbon was obtained up to about 15,000 cycles. move transversely to the bars, appeared 0.002 in., and it was masked to a length of Wente left the company in 1916 for well adapted to making photographic about 0.2 in. It was imaged on the film graduate study and returned in 1918. In records of the variable-density type. with a 2 : 1 reduction. With the slit width the meantime Dr. I. B. Crandall had While a variable-density record would 0.002 in., the light could be modulated made a theoretical analysis of the air- not give as much information to the eye 100% by a of each ribbon of film damping, and improved the instru- as a variable-area record, it could be 0.001 in. amplitude. Since the ribbon ment by means of grooves of appropriate analyzed by instruments of the micro- need be only slightly wider than its size and shape in the ba~kplate.~~For densitometer type. The faithfulness of the double amplitude, thick enough to be measurement purposes it was essential to recording could be checked by playing it opaque, reasonably easy to handle and calibrate the condenser transmitter, and back. (The previous oscillographic re- long enough between supports to make Wente accomplished this by working out cordings had not been designed for the deflection substantially uniform the theory of the thermophone, which playing back.) throughout the length of the slit, it can enabled him to make a reliable pressure Some of the recordings were played in be extremely light and readily put under ~alibration.~~Free field calibrations were May 1922 for Craft and others. A few enough tension to place its mechanical made later, using a Rayleigh disk as months later apparatus-development en- resonance above the required audio reference. In a later design,47which was gineers were requested to construct an range. Rather than attempting to control used commercially for sound recording, electrically interlocking driving system the resonance by damping beyond that the sensitivity was greatly increased, in for camera and recorder. Further demon- obtainable electromagnetically, an elec- part by use of aluminum alloy 0.001 in. strations were given in December 1922. trical low-pass filter was used in the in- thick instead of 0.002 in. steel for the In these recordings the principle was put, to prevent the passage of any im- diaphragm, and in part by not carrying recognized, that for linear relations be- pulses of high enough frequency to ex- the response as far into the high-fre- tween exposing light and print transmis- cite the resonance. However the cutoff quency range. (In 1931 W. C. Jones sion, the product of positive and negative was not too far below the frequency of published a pressure calibration curve “gammas” should be unity.61,62 resonance to permit a considerable rise for a 8394 transmitter which showed a in amplitude just before cutoff, the maxi- rapid drop above about 7000 ~ycles.4~) Light Valve. The grating type of modu- mum being at about 7000 cycles. This The condenser tramsmitter is rated as a lator had several drawbacks, one of rise was regarded as advantageous in that a very insensitive device, but it is of in- which was diffraction by the grating. it compensated for loss of high-frequency terest that a diaphragm deflection of a Because of these difficulties, Wente in response due to image spread in the film. millionth of an inch will give a fifth of a January 1923 proposed using a two- For monitoring, a photocell behind the volt, the gradient in the space between string light val~e.m-‘j~*~Such a valve was film picked up some of the light which electrodes being 200 v per mil. It is the ex- ready for test a month later. The tension went through the film. treme stiffness of the diaphragm which on the ribbons was adjusted to bring The subject of sensitometry for sound- makes the sensitivity low. their resonance to 6500 cycles. Condens- tracks of the variable-density type also ing lenses imaged the light source on the received attention from many other Photograghic Recordings. The condenser slit between the ribbons, and an objec- writers for a number of years after the transmitter with amplifier gave better tive lense imaged the valve slit on the advent of photographic sound. waveshape traces, but the narrow mirror film. In the matter of the frequency range of the bifilar (or Duddell) oscillograph Results with the light valve were attained in the early light-valve record- causes diffraction effects which make the definitely better than with the previous ings, MacKenzie shows an overall (light- light-spot at the film blurred or fuzzy. modulators, and arrangements were valve input to photocell output) curve Prof. A. C. Hardy showed5g that this made for tests on a larger scale. A record- which was substantially flat to 5000 cy- trouble could be largely eliminated by ing studio was set up in 1923 and sound cles, a figure not far from what could be radical changes in the optical system in pictures made for demonstration pur- obtained at the time with disks. which the oscillograph vibrator is used, poses. but his analysis was not published until In the latter part of 1922 and subse- Recorder. The Western Electric record- 1927 (in time to be of much help in the quently, much of the study of film emul- ing machine employed a sound sprocket, General Electric recording develop- sions, exposures and developments was having a filtered drive and protected by ments, but the Western Electric experi- carried on by Dr. Donald MacKenzie. a feed sprocket from jerks from the maga- ments with the oscillograph were before He showed that by running the lamp at zine~.~The film was exposed while on 1920). slightly over-voltage, it was possible ade- the sound sprocket. For synchronism An article in a British Journal (1920) quately to expose positive film, which the camera and recorder were driven by came to Wente’s attention, describing thereafter was the standard sound-re- selsyn motors. experiments of Prof. A. 0. Rankine in cording stock. The relatively fine grain transmission of sound over a beam of of the positive stock was of great benefit Soundhead. For reproduction from pho- light. The light modulator, in which a from the standpoint of resolution and low tographic soundtracks the Western Elec- rocking mirror caused an image of one background noise. tric Co. built a “soundhead,” to be

298 June 1955 Journal of the SMPTE Volume 64 mounted under the picture projector,52-% motion-picture industry (except for the Hoxie called his optical phonograph similar in many respects to that pre- case of Fox Movietone and Warner Vita- the Pallophotophone, meaning “shaking viously mentioned as used in the Fox- phone) is discussed in another section of light sound.’’ We do not know the iden- Case development. I shall come back to this paper. tity of the Greek scholar. In another ex- the subject of the mechanical features of perimental development, Hoxie caused the film-motion system, so shall mention Developments at General Electric Co. the vibration of a sound-pickup dia- here only some optical and electrical Interest in photographic sound re- phragm to rock the mirror. This device, features. The scanning light on the film cording at the General Electric Co. in called the Pallotrope, was used with a was an image of a mechanical slit, il- Schenectady stems from the develop- photocell as a photoelectric microphone. luminated by a low-voltage incandescent ment prior to 1920 of a photographic lamp, with condensing lenses. The fila- telegraph recorder for radio reception,‘j6 Narrow Sound Track Found Suj’icient. mentwas a close-wound helix withstraight by Charles A. Hoxie. Transoceanic radio Hoxie continued his experimenting for horizontal axis. The photocell and pre- service was by long waves, and static several years before any decision was amplifier were cushion-mounted to pre- interference caused the loss of many reached to embark on an all-out program vent microphonic noises. Owing to the letters. It was thought that a visual record of developing a system of sound for mo- very high impedance of the photocell and of the incoming , even though tion pictures. One of Hoxie’s experi- its small output, a very short (low-ca- mutilated by static, might be deciphered ments which undoubtedly played a part pacity) connection to the first amplifier at leisure in many cases in which the in interesting executives in such a pro- tube is important. The signals were forever lost if the operator, gram was that of reproducing with part brought the level up to about equal to depending on ear alone, failed to recog- of his track width masked. The de- that of the disk pickups. nize a letter. velopment of the General Electric model For the usual reception, by ear, the in- of the Duddell oscillograph had centered Standard Speed. In the early theater in- cominc continuous- code signals in the General Engineering Laboratory stallations most projectors were equipped were heterodyned to give interrupted (where Hoxie worked) and it was ex- for both disk and film reproduction. It tones of , short for dot tensively used as a laboratory tool was obvious that for sound pictures the and longer for dash. Hoxie’s recorder throughout the company. With such a recording and reproducing speeds must made an oscillographic record of these background it would be natural to think be closely held to a standard. The prac- code tones, on a moving strip of of a photographic sound track as showing tice had become widespread of projecting sensitized paper. Instead of actuating a the outlines of the sound waves. silent pictures at considerably higher receiver diaphragm the electrical signals In any case the wide soundtracks speeds than that of the camera, which vibrated a reed armature, which, through made in the Hoxie equipment were of the had for years been nominally 16 pictures/ a delicate knife-edge arrangement, im- variable-area type. A spot of light moved sec or 60 ft/min. The higher projection parted rotary motion to a mirror, which parallel with the slit, illuminating a speeds shortened the show so that more caused a small spot of light to dance back larger or smaller fraction of its length. shows could be run in a day, and the and forth across the sensitive strip. However, the active edge of the light public had become inured to the fast Since the rode recorder vibrated at spot was by no means sharp. While ex- action. But there was a better justification audio frequency, it was a short step to try perimenting with reproduction from this in that flicker was much reduced. it and modifications of it for recording sound track, Hoxie observed that mask- For pictures with sound on film there voice, and this was one of the many ex- ing off part of the track had little effect was further benefit from increased speed periments which Hoxie tried which on the sound except some reduction in in that it resulted in better high-frequency started him on more systematic experi- volume. He repeated the experiment with response and, in some degree, reduced mentation in the field of photographic still more of the track masked off, until percentage of speed fluctuation. A speed sound recording. Negative film was used he was using only a sample, about & in. of 85 ft/min for silent pictures had been at first, in order to get adequate ex- wide. This experience was sufficient to recommended for a standard, but prac- posure, but Hoxie was among the first to demonstrate that a track wide enough to tice varied widely. A speed of 90 ft/min appreciate the advantage of the finer- show the wave outlines was by no means or 24 frames/sec was chosen for both of grain positive film. necessary for sound reproduction. The the Western Electric sound-picture sys- As in the case of the telegraph re- narrow strip being scanned was obviously tems (sound on disk and sound on film) corder, the track ran down the middle of a variable-density record of the sound. and this became the standard. On the the film, and was nearly an inch in At that early stage of the experiment- theory that exhibitors would demand the width. In Hoxie’s recording and repro- ing we had not seen it demonstrated by option of running silent films at other ducing machine the film was drawn over actual accomplishment that a satisfactory speeds, the Western Electric engineers a physical slit on which intense light was variable-area recording could be confined adopted a driving system with an ac- concentrated. The width of the slit was within so limited a band, but at any rate curate control which could be made in- about 0.001 in. Since an open slit would this test proved that a photographic active at the option of the projectionist.” quickly fill with dirt, a wedge of fused sound record could be placed along the Either a repulsion motor or a d-c motor quartz was ground to a thin edge and side of the picture without stealing more might be used. For 90 ft/min a 720-cycle cemented in place between the metal picture width than could be tolerated. generator fed a bridge with one arm edges which formed the slit. The face tuned to 720 cycles. At the correct speed against which the film was to run was Loudspeaker and Phonograph Dcvelot- the bridge was balanced, but if the speed then lapped and polished. A photocell ments. Another factor which undoubtedly was not correct the unbalance gave rise close behind the film picked up the influenced General Electric executives to a correcting current which increased transmitted ligh‘t, and an amplifier and toward increased interest in sound was or decreased the motor speed as required. loudspeaker completed the reproducing the success of the loudspeakers developed system. The results were highly gratify- by C. W. Rice and myself for broadcast Commercialization. In January 1927 ing. Theisen6 says that Hoxie’s first sound radio reception.38 The coil-driven (or Electrical Research Products Inc. was recorder was completed in 1921, and with “dynamic”) paper cone, freely sus- formed as a subsidiary of Western Elec- it he recorded speeches by President pended, surrounded by a baffle and tric and the Telephone Co. to handle Coolidge, the Secretary of War and driven by an amplifier with adequate commercial relations with motion-pic- others, and the recorded speeches were undistorted power, so far surpassed its ture producers and exhibitors. broadcast over Station WGY (Schenec- predecessors in quality of reproduction The adoption of sound systems by the tady) in 1922. that within a few years its use for radio

Kellogg: History of Sound Motion Pictures 299 receivers and phonographs became prac- Brunswick electrically recorded disks). so that with the cooperation of that de- tically universal. * Our part in the phonograph project was partment, pictures with sound could be Following the loudspeaker develop- tapering off, freeing some of the personnel made. A number of demonstrations were ment, the success of the electric phono- to devote time to the newer develop- given in 1926 and 1927, using this equip- graph helped to make the sound motion ment. Our group, however, had inade- ment. Motion-picture produrers showed picture seem like a logical next project. quate background in optics and pho- interest, but no contracts were made at tography. Professor A. C. Hardy was en- that time. Chester W. Rice. I trust that I will be ex- gaged as consultant and soon did us two cused if I take this opportunity to pay a An incident of much interest to those invaluable services : he straightened US who were connected with thp photo- brief tribute to my colleague, whose out on a number of optical and photo- vision and initiative were largely re- graphic recording prqject was a visit to graphic questions, and he recommended Schenectady in December 1925 by E. I. sponsible for our undertaking the loud- that we engage the services of L. E. Clark, speaker project. His thoroughness and Sponable from the Case Laboratories.6 then completing some advanced work at He showed and demonstrated the com- tireless energy insured that no hopeful Massachusetts Institute of Technology. lead was left unexplored. He brought to bined camera and sound-recording sys- “Pete’s” presence was a guarantee that tem which he and his associates had de- bear on his work an extraordinary mea- we would not again get off the beam on sure of ingenuity and mastery of engi- veloped, giving us the benefit of his ex- optical questions, but his associates at perience and participating in some neering and physical principles, which he General Electric, then at was constantly supplementing by study, demonstrations. However, no arrange- headquarters in New York, and later in ments for combining the efforts resulted. and his standards of excellence would Hollywood, carry a memory of some- permit no compromise with an inferior thing far more cherished than his valu- Thr Road-Show Wings. The first public result. able technical help. entertainment picture to be shown, with No one could have been more scrupu- the General Electric developed sound lously fair and generous in giving credit Variable-Area System Chosen. A funda- system, which by this time had been to other workers. His death in 1951 was a mental question on which we took Prof. named the Kinegraphone, was a story of great loss to his associates and to science. Hardy’s advice was in regard to the ad- the Air Force activities in World War I, vantages of the variable-area type of entitled Wings and produced by Para- C. W. Stone’s Leadership. In addition to soundtrack.61At the time of Hoxie’s tests mount. The sound effects were added L. T. Robinson, head of the General En- with a masked track, the only tracks that after the picture had been shot. The sys- gineering Laboratory, the man who had been made, sufficiently narrow and tem and equipment were demonstrated played the major role in initiating and still fairly satisfactory, were of variable and briefly described by H. B. Marvin.Q promoting a large-scale project for de- density. A better understanding and ap- veloping talking pictures, was C. Wines was exhibited in 1927 as a w. plication of optical design was needed to Stone, manager of the Central Station “road show” (about a dozen sets of make clear, sharp-edged variable-area Dept., who had taken great interest in equipment having been supplied), for tracks within permissible limits of all of the sound developments. His en- few motion-picture theaters at the time width. 59+60 thusiasm, confidence and influence en- Wzngs was shown were equipped for With the right kind of lenses and opti- couraged those who were engaged in de- reproduction. Multiple- cal design, an imaged slit soon displaced velopment, helped to secure the financial unit con?-and-baffle type loudspeaker^^^ the contacting physical slit with which backing and established fruitful contacts were used, with a bank each side of the ‘the first tracks had been made. Hoxie’s outside the company. screen. The sound-reproducing device or special galvanometer was not ad+ “head” was mounted on the top of the Practical designs; Assistance of Prof. A. C. quately damped, but General Electric projector, no standard sound offset hav- Hardy and L. E. Clark. When, about 1925, had long since been building oil-damped ing been established at the timr the ap- a program of developing commercial oscillographs of the Duddell type, whose paratus was designed. The picture sound-on-film equipment was under- response was good up to 5000 cycles. width was reduced from 1 in. to f in. to taken, Robinson was made responsible The optics of the recording system are make room for a soundtrack. Ninety for the general program, and, together similar in principle to those of the oscillo- ft/min had by this time been agreed with others in the Research Laboratory, graph, as explained in one of Hardy’s upon for film speed. I was asked to assist in problems where papers.6gProf. Hardy had shown how im- There were many, even of the most en- there seemed to be call for research. En- portant design improvements could be thusiastic advocates of sound-picture de- gineers in the General Engineering and made, greatly increasing the light in- velopment at General Electric, who did Research Laboratories had had ex- tensity at the film. An optical system was not think of the chief function of the syn- perience in sound, first with loud- designed60 using a regular oscillograph chronized sound as giving speech to ac- speakers3*and then in cooperation with galvanometer, and follo wing suggestions of tors in plays, but there was high confi- the Brunswick Balke Callender Go., Prof. Hardy and of L. E. Clark. dence that there was a large potential electrical recording and reproduction for The general mechanical features of the market for sound systems for furnishing phonographs5* (the work represented in first recording machines were due prin- sound effects and background music and the Brunswick Panatropesl and the cipally to Hoxie, while H. R. Marvin (of providing voice for lectures and speeches. the General Engineering Laboratory) G.E.-Westinghouse-RCA Working *Many of the elements of this type of loud- designed amplifiers, optical systems and speaker, such as coil drive, cone diaphragms other necessary equipment. High-quality Arrangements and the baffle had been proposed individually microphones were available in the West- At the time that the synchroniLed by early inventors, but not in the full combina- sound development was taking shape, the tion. Nor, I believe, was the principle of plac- ern Electric Condenser Transmitter (de- ing the mechanical resonance of the diaphragm veloped by E. C. Wente of the Bell Lab- three-cornered arrangement between (with its suspension) at or below the lowest which was used in broad- General Electric, Westinghouse and RCA important frequency proposed, except that cast studios and had been an essential was in effect. RCA was the sales outlet Adrian Sykes (US. Pats. 1,711,551 and for all radio and kindred equipment. 1,852,068) advocated it for a microphone. The tool in the lo~dspeaker~~and phontograph Farrand loudspeaker (U. S. Pat. 1,847,935, filed developments. 51 Manufacturing was divided between 1921. See Radio Club of America, Oct. 1926) General Electric had a well estab- General Electric and Westinghouse. Re- had a large cone, coil-drive and low resonance- lished motion-picture laboratory under search and development continued to be frequency, but no baffle or associated power am- carried on at both manufacturing com- plifier. It had considerable commencial succcss the direction of C. E. Bathcholtz, for during the 1920’s. general company and puhlicity service, panies, and before production was

300 June 1955 Journal of the SMPTE Volume 64 started, designs were coordinated be- Kintner. A group under Max C. Batsel audience as successfully as the use of tween them and had also to be accepta- was responsible for development and de- short horns. The first successful units of ble to RCA, which maintained a Tech- sign of commercial equipment. One of this type were developed by J. D. Seabert nical and Test Dept. in New York, to this group was J. D. Seabert, whose con- in 1929 (then of Westinghouse). The pass on performance. tribution to the theater loudspeaker horns used at first expanded from about At Schenectady, in view of the pros- problem will be described in the para- the cone area to an opening abut 3 ft by pects of manufacturing on a much larger graph with that heading. Hanna’s 4 ft. The name “directional baffle” was scale than could be handled in the Gen- analysis of the damped flywheel prob- used to distinguish these horns, whose eral Engineering Laboratory, the film lem‘j9laid the foundation for the highly primary function was to confine the ra- project had been transferred (1927) to successful rotary stabilizer discussed diation within a limited angle, from the the Radio Dept. where it was under the under that heading in the section deal- small-throat horns whose basic function direction of E. W. Engstrom. The change ing with Mechanical Systems. was to load the diaphragm, in addition to brought new personnel into the activity. confining the radiation. The directional The names of E. D. Cook and G. L. Organization of RCA Photophone, Inc. baffle type of unit was the subject of later Dimmick deserve mention. developments by Dr. H. F. Olson and RCA Photophone, Inc. was organized his Developments at Westinghouse in 1928 as an RCA subsidiary to carry on In spite of the benefits of directive 1 Engineers at the Westinghouse Elec- commercial exploitation of the sound-on- baffles, in many motion-picture theaters tric and Manufacturing Co. in East film system. Carl Dreher (later with satisfactory speech reproduction was not Pittsburgh did not turn their attention to RKO) was its first chief engineer, fol- achieved until had been ap- photographic sound recording until lowed in 1929 by Max C. Batsel from the plied to reduce reverberation. about 1926 when the project at Schenec- Westinghouse Co. A laboratory was es- tady had gained some momentum. tablished in New York to which a num- Location Equipment. The RCA equip- One of the first research projects under- ber of engineers were transferred from ment also included a truck for location taken was to adapt the Kerr cell to the Technical and Test Dept. of RCA. and newsreel service.’6 With batteries for photographic recording. The develop- power supply, the truck carried a motor ment was described to this Society in 1928 New Deskns of Commercial Units. Be- generator for driving apparatus designed by V. K. Zworykin, L. B. Lynn and C. R. tween the launching of the Wings show for 60-cycle operation, and a studio-type Hanna.‘j8Nitrobenzene has the property and the offering by RCA Photophone, film recorder, to be driven in synchro- of rotating the plane of polarization of a Inc., of a commercial sound system,* a nism with a cable-connected camera. light beam, when the liquid is subjected to number of design changes and advances For more remote or inaccessible loca- an electrical field at right angles to the had been made. C. L. Heisler had de- tions, a single-film system was provided, direction of the light. The amount of signed a new recording machine (R-3) with portable batteries and amplifier, rotation depends on the square of the field and a combined picture and sound pro- governed direct-current camera motor, gradient. Practically, several hundred jector (P-2))’O both of which embodied and a sound attachment, mounted on the volts per millimeter are required. Nicol new principles in film motion. A sound top of the camera.74The first commercial polarizing prisms are used on each side attachment or “soundhead” was de- uses of RCA Photophone recording equip- of the cell and rotated to extinguish the veloped, by which existing silent projec- ment were for newsreel service. Two types light at minimum applied voltage. With tors could be adapted for sound. The of light modulator were employed in the increase of voltage, the transmitted light offset between picture and sound had earliest Photophone single-film location then varies as the sine of the increase in meantime been standardized at 14; equipments, one of which used a gal- angle of rotation. in., with the soundhead mounted under vanometer designed by W. 0. Osborn and One of the design problems is to keep the projector. Because of the much more K. A. Oplinger, under the direction of within satisfactiory limits the distortion stringent requirement for accurate and C. R. Hanna, with optics generally resulting from the nonlinear relation be- constant speed for sound than for picture, similar to those of the studio system, and tween voltage and transmitted light, the driving motor was made part of the the other the Kerr cell (or Carolus cell) Another difficulty is that commercial soundhead, and the projector mechanism system developed by L. B. Lynn and V. nitrobenzene is yellow, absorbing the driven from the soundhead through K. Zworykin.68 photographically valuable blue light. gears. The first commercial soundhead to Location equipment (sound trucks) of The investigators were able by double be offered by the RCA group (desig- improved design followed within a short distillation to reduce very largely the nated as PS-1) was of Westinghouse de- time. Of special interest was a new optical absorption of blue light. A third problem sign, but the manufacturing was carried system requiring only 3 w for the lamp.76 on by both companies. was avoidance of electrical arcs through Disk Equipment. Although the RCA the liquid, which quickly contaminate it. Theater Lohdspeakers. The flat baffle group was convinced of the inherent ad- Proper choice of electrode material and vantages of sound on film for motion- surfaces, and purification of the liquid type of loud~peaker~~used in the Wings equipment and in almost universal use picture sound, disk equipment was made it possible to produce cells which wanted in all of the earlier theater in- were regarded as practical. for home receivers, while excellent for music and sound effects, had not proved stallations, and accordingly combined The unique property of the Kerr cell sound-on-film and synchronous disk light modulator which makes it of special satisfactory for speech reproduction in reverberant theaters. While a certain equipment was designed and built by the interest is its extreme speed. The only G.E. and Westinghouse companies and limitation is in the ability of the modula- kind of directivity can be had by using arrays of direct-radiator ldspeakers, supplied by RCA Photophone, Inc. tion-voltage supply system to charge the A number of developments and in- extremely small capacity of the cell. As vibrating in phase, this did not confine the radiation in the direction of the ventions took place at both of the manu- contrasted with this, other light-modula- facturing companies which did not come tion systems either involve moving * H. B. Franklin in Sound Motion Pictures2 gives into commercial use for several years, mechanical elements, or electrical dis- May 14, 1928, as the date of an announcing and these will be described presently. charges through gases, which have defi- advertisement in New York and Los Angeles nite frequency limitations. papers; however the Progress Report, Trans. Commercialization. The establishment of Zworykin, Lynn and Hanna were in SMPE, No. 31, 438, May 1927, states that Photophone equipment is to be sold direct to commercial relations with picture pro- the Westinghouse Research Laboratory, theaters, and that recording efforts would be ducers is described in the latter part of which was under the direction of Mr. concentrated on music scores. the following section.

Kellogg: History of Sound Motion Pictures 301 Bibliography and References and Acoustics and Architecture, McGraw-Hill 50. H. A. Frederick, “Recent advances in wax Book Co., New York, 1932. recording,” Trans. SMPE, No. 35, 709- 1. Lester Cowan, Recording Sound for Motion 29. See refs. 400 et seq.- on lamp develop- 729, 1928. Pictures, McGraw-Hill Book Co., New York, ments. 51. E. W. Kellogg, “Electrical reproduction 1931; H. G. Knox, “Ancestry of sound 30. T. Mishima, “Nickel-aluminum steel for from phonograph records,” Trans. AIEE, pictures,” Chap. 1. permanent magnets,” Stahl und Eisen, 53: 46: 903, June 1927. 2. H. B. Franklin, Sound Motion Pictures, 79, 1933; and US. Pats. 2,027,994 to 52. E. 0. Scriven, “Western Electric sound , Doran and Co., 1929. 2,028,000 incl; also W. E. Ruder, “New projecting systems for use in motion picture 3. Academy of Motion Pictures Arts and magnetic alloys,” Proc. IRE, 30: 437, 1942. theatres.” Trans. SMPE, No. 35, 666-678, , Motion Picture Sound En,qimerin,q, 31. Ref. 6, also gives the references Annul. dcr 1928. D. Van Nostrand & Co., New York, 1938. Phys., 103, 1901, and Phys. Zeit., No. 34, 53. H. Pfannenstiehl, “A reproducing machine 4. J. G. Frayne and H. Wolfe, Elements of 498, 1901; Ref. 5, p. 421, and Crawford, for picture and sound,” Trnns. SMPE, Sound Recording, J. Wiley & Sons, New ref. 32, refer to an article by Ruhmer in the NO. 38, 253-267, 1929. York, 1949. ScientiJc American, July 29, 1901. 54. H. M. Stoller, “Synchronization and speed 5. W. E. Theisen, “Pioneering in the talking 32. Report of the Historical Committee, Jour. control of synchronized sound pictures,” picture,” Jour. SMPE, 38: 415-444, Apr. SMPE, 16: 105-109, Jan. 1931; Merritt Trans. SMPE, No. 35, 696-708, 1928. 1941. Crawford, “Pioneer experiments of Eugene 55. I. M. Green and J. P. Maxfield, “Public 6. E. I. Sponable, “Historical development of Lauste in recording sound,” Jour. SMPE, address systems,” Trans. AIEE, 42: 64, sound films,” Pt. 1-2, Jaw. SMPE, 48: 17: 632-644, Oct. 1931. 1923. 275-303, Apr. 1947; Pt. 3-7, ibid., 407-422, 33. R. W. Paul, “Kinematographic ex- periences,’’ Jour. SMPE, 27: 495-512, 56. E. C. Wente, US. Pat. 1,812,389, “Acoustic May 1947. device” (i.e. loudspeaker). 7. F. H. Richardson, “What happened in the Nov. 1936; also, Thomas Armat, “My part in the development of the motion 57. E. C. Wente and A. L. Thuras, “A high beginning,” Trans. SMPE, No. 22, 63-114, efficiency receiver of large power capacity 1925. picture projector,” Jour. SMPE, 24: 241- 256, Mar. 1935. (These are of interest, for horn type loud speakers,” Bell Sys. 8. T. A. Edison, U.S. Pat. 200,521, 227,679. Tech. J., Jan. 1928, p. 140. 9. Terry Ramsaye, History of fhe Motion though they do not deal with sound.) 34. J. T. Tykociner, “Photographic recording 58. Samuel L. Warner, Honor Roll Award, Picture, Simon & Schuster, New York, 1925. Jour. SMPE, 48: 443-446, May 1947. 10. Terry Ramsaye, “Early history of sound and photo-electric reproduction of sound,” pictures,” Trnns. SMPE, No. 35, 597-602, Trans. SMPE, No. 16, 90-119, 1923. 59. A. C. Hardy, “Optical system of the 1928. 35. Hans Vogt, Joseph Massole and Josef oscillograph,” J. Opt. Sac. Am. 74: 505, Engl, U.S. Tri-Ergon Pats. 1,512,681 ; June 1927. 11. A. Dickson and W. K. L. Dickson. History 1,534,148; 1,555,301; 1,557,678; 1,558,032; 60. A. C. Hardy, “The optics of sound re- of th Kinetograph, and Kineto- 1,566,413; 1,590,185; 1,597,323; 1,608,261; Phonograph, Albert Bunn, N.Y., 1895. cording systems,” Trans. SMPE, No. 35, 1,628,377; 1,634,201; 1,756,681; 1,825,598; 12. W. K. L. Dickson, “A brief history of the 760-777, 1928. 1,713.726; Re. 20,621; 2,140,003 and Kinetograph, Kinetoscope and Kineto- 61. A. C. Hardy, “The rendering of tone values others. Phonograph,” Jour. SMPE, 27: 435455, in photographic recording of sound,” 36. L. de Forest, “The Phonofilm,” Trans. Dec. 1933. Trans. SMPE, No. 31, 475-491, 1927. SMPE, No. 16, 61-75, May 1923; “Phono- 62. L. A. Jones, “On the theory of tone re- 13. Will H. Hays, See and Hear, p. 40, Motion film progress,” Trans. SMPE, No. 20, 17- Picture Producers and Distributors of production with a graphic method for the 19, 1924; “Recent developments in the solution of problem,” Jaw. SMPE, 16: America, New York, 1929. Phonofilm,” Trans. SMPE, No. 27, 64-76, 14. E. H. Amet, U.S. Pat. 1,124,580 and 568-599, May 1931. 1927; “Pioneering in talking pictures,” 63. E. C. Wente, US. Pat. 1,638,555, “Trans- 1,162,433, 1915. Jour. SMPE, 36: 41-49, Jan. 1941. 15. W. H. Bristol, “An electrical synchronizing lating devices” (light-valve). 37. Theodore W. Case, Honor Roll Award, 64. Donald MacKenzie, “Sound recording and resynchronizing system for sound Jour. SMPE, 48: 437-440, May 1947. motion picture apparatus,” Trans. SMPE, with the light valve,” Trans, SMPE, No. 38. Chester W. Rice and E. W. Kellogg, 35, 730-747, 1928. No. 35, 778-789, 1928; and “New “Notes on the development of a new type synchronizing apparatus for 16 mm films of hornless loud speaker,” Trans. AIEE, 65. T. E. Shea, W. Herriott and W. R. Goeh- with disk records,” Jour. SMPE, 74: 361- 44: 461, Apr. 1925. ner, “Principles of the light valve,” Jour. 365, Mar. 1930; also U.S. Pat. 1,234,127, 39. Carl L. Gregory, “Resurrection of early SMPE, 18: 697-731, June 1932. 1917. motion pictures,” Jour. SMPE, 42: 159- 66. C. A. Hoxie, “A visual and photographic 16. , Mein Weg Mit dLm Film, 169, Mar. 1944. device for recording radio signals,” Proc. Max HesseVerlag,Berlin Schoneberg, 1936; 40. Theodore W. Case, “Thalofide cell, a new IRE, 9: 506, Dec. 1921; and U.S. Pat. Bk. Rev., Jour. SMPE, 332, Sept 1937; photoelectric substance,” Phys. Rev., Apr. 1,758,794 (filed Aug. 1927). also Brit. Pat. 22,563, 22,564, 22,565. 1920, and J. Opt. Sac. Am., No. 6, 398, 67. H. B. Marvin, “A system of motion pictures 17. T. A. Edison, U.S. Pat. 1,182,897, 1916; 1922; U.S. Pats. 1,301,227 and 1,316,350. with sound,” Trans. SWPE, No. 33, also Daniel Higham, US. Pat. 1,036,235, 41. Theodore W. Case, “Aeo-Light,” US. 86-102, 1928. 1,054,203, 1,036,236 and 1,226,883. Pat. 1,816,825. 68. V. K. Zworykin, L. B. Lynn and C. R. 18. E. W. Blake, Am. J. of Scieme, No. 16, 54, 42. Edward B. Craft, Honor Roll Award, Hanna, “Kerr cell method of recording 1878. Jour. SltfPE, 48: 440-443, May 1947. sound,” Trans. SMPE, No. 35, 748-759, 19. A. C. Hardy and F. H. Perrin, The Primiplcs 43. J. I. Crabtree, “The work of Edward 1928. of Optics, McGraw-Hill Book Co., New Christopher Wente,” (1 935 Progress Medal 69. C. R. Hanna, U.S. Pat. 2,003,048 (condi- York, 1932. Award), .Jaw. SMPE, 25: 478-482, Dec. tions for critical damping). 20. V. K. Zworykin and E. G. Ramberg, 1935. 70. E. W. Kellogg, “-4 review of the quest for Photoelectricity and Its Application, J. Wiley & 44. E. C. Wente, “A condenser as a uniformly constant speed,” Jour. SMPE, 28: 337-376, Sons, New York, 1949. sensitive instrument for the absolute Apr. 1937. 21. L. R. Koller, “Characteristics of photo- measurement of sound intensity,” Phys. 71. H. F. Olson, “Recent developments in electric cells,” Trans. SMPE, No. 36, Rev., July 1917; US. Pat. 1,333,744. theater loudspeakers of the directional 921-939, 1928. 45. I. B. Crandall, “The air damped vibratory baffle type,” Jour. SMPE, 78: 571-583, 22. M. F. Jamieson, T. E. Shea and P. H. system: theoretical calculation of the May 1932.

Pierce, “The photoelectric cell and its condenser transmitter,” Phys. Reu., 449, 72.~~ Louis Malter. “Loudsueakers and theater method of operation,” Jour. SMPE, 27: June 1918. sound reproduction,” Jour. SMPE, 14: 365-385, Oct. 1936. 46. E. C. Wente, “Electrostatic transmitter,” 611-622, June 1930. 23. L. de Forest, U.S. Pat. 841,386, 841,387, Phys. Rev., 498, May 1922. 73. H. F. Olson and F. Massa, Applied Acoustics, 879,532. 47. W. C. Jones, “Condenser and carbon P. B!akiston & Son, Philadelphia, 1934. 24. See refs. 392-399. microphones, their construction and use,” 74. C. R. Hanna, “The Mitchell Recording 25. Frederick V. Hunt, Electroacoustics, J. Jour. SMPE, 16: 3-22, Jan. 1931. Camera, equipped interchangeably for Wiley & Sons, London and New York, 48. Frank H. Lovette and Stanley Watkins, variable area and variable density sound 1954. “Twenty years of talking movies, an recording,” Trans. SMPE, No. 38, 312-317, 26. T. A. Edison, US. Pat. 307,031; and J. A. Anniversary,” Bell Telephone Magazine, 1929. Fleming, U. S. Pat. 803,684. Summer, 1946. 75. Harry W. Jones, “The modern newsreel,” 27. V. Poulsen, US. Pat. 661,619, 789,336, 49. J. P. Maxfield and H. C. Harrison, “Meth- ‘ Jour. SMPE, 14: 204-208, Feb. 1930. 873,078, 873,083. “Der Telegraphon,” ods of high quality recording and re- 76. P. M. Robillard and E. B. Lyford, “Recent Awl. ah Physik, 3, 1900. producing of music and speech based on developments in RCA Photophone portable 28. Wallace C. Sabine, Collected Papers on telephone research,” Trans. AIEE, 45: recording equipment,” Jour. SMPE, 16: Acoustics, Harvard University Press, 1922 ; 334, 1926. 269-276, Mar. 1931.

Another installment of this paper will be published in the Ju(y Journal

302 June 1955 Journal of the SMPTE Volume 64