discussion of a history of modern radio-electronic technology · discussion of"a history...

PROCEEDINGS OF THE IRE

Discussion of "A History of Some Foundations of

Modern Radio-Electronic Technology"

Critique by Lloyd Espenschied*In tracing their own inventing over the

years, Hammond and Purington' recall in-terestingly the evolution of our modern artfrom the time of spark wireless telegraphyas of about 1910. But they give the impres-sionI that their inventing played a morefoundational role than was the case. Withthe possible exception of Fritz Lowenstein'srealization of the amplifier out of de Forest'sgrid audion detector, which appears to havebeen conceived before he became associatedwith Hammond, it may be said that theroots of our modern technology trace backgenerally to sources other than the Ham-mond Laboratory. Actually, Hammond'swork was conducted in secret, as the authorsaver, while speculative patents, filed pro-lifically, were long held in the Patent Office.Meanwhile the advance rolled on, with itsliterature accumulating, generally obliviousof the Hammond group. Hence claims madein the paper to "firsts" and to the establish-ment of "principles" are in need of amenid-ment, as discussed below. The writer regretshaving to turn critic, for he welcomed therendering of the Hammond story. As it is,the paper will contribute more to technicalhistory by calling for additional evidence.X\e follow the sections of the paper be-ginning with Section II.

THE RADIODYNAMIC TORPEDO (SECTION II)Hammond is best known for his long pur-

suit of the problem of directing torpedoes byradio control. As still earlier pioneers in thisfield, mention is made in the paper of a pairof British inventors and of N. Tesla. Butsingularly omitted from mention is the onewho received from the U. S. Patent Officethe underlying claims, one of which reads:The combination with a source of electrical wavesor disturbances of a moving vessel or vehicle andmechanism thereon for steering or operating thesame, and controlling apparatus adapted to beactuated by the influence of the said waves ordisturbances at a distance from the source, as setforth.

This is Patent No. 660,155, one of a pair,iiieanis and method patents, granted toLieutenant (later Admiral) Bradley A. Fiske,October 23, 1900. Fiske had filed only a fewmonths after Tesla in 1898 and was able toswear back of Tesla and obtain the primaryclaims. In 1912 Hammond wrote from Wash-ington, D. C., a letter2 inquiring about thispatent, saying "I am very much interestedin Patent No. 660,155 . " and going on toobserve: "This is the first record of anykiitd which completely covers the art ofwireless control of mechanisms." Thus, onewNonders why Fiske is not cited as a pioneer,or the pioneer, in the present paper. In the

* Received by the IRE, December 2, 1957.1 PROC. IRE, vol. 45, pp. 1191-1208; September,

1957.2 Letter of January 11, 1912, written to the West-

ern Electric Co., 463 West St., New York, N. V.

summer of 1915 Hammond was selling to aCongress worried by the European war thenraging, his system of wireless control oftorpedoes. Fiske became concerned lest hispatents be infringed and issued a publicstatement explaining how he came to makethe invention, and observing that, "Mr.John Hays Hammond, Jr. has done splendidwork based on my original patent."3 In hisautobiography of 1919 Fiske wrote, " . . . Ido not know of Mr. Hammond ever givingme credit for having suggested the planoriginally, or of his disclaiming the creditgiven him for it in many accounts of hisachievements. "4

Of course it was quite impossible for anyof the early inventors to get very far on thisproblem, so crude was early radio; and evenafter the revolutionary high-vacuum tubecame along, to reach an underwater vesselwith control signals was most difficult. TwoWorld Wars have now occllrred with nomilitary use of the radio-controlled torpedo;it is just as well, except for the futile ex-penditure of technical effort and publicmoney.

Among the "principles" claimed to havebeen developed in the 1910-1914 period isthat of the automatic stabilization of thecourse of a torpedo by means of the gyro.5Yet one reads in the Encyclopaedia Britan-nica of 1910-1911, eleventh edition, underthe article on "Torpedo," of gyrocontroltrials in 1896 which "demonstrated thefeasibility of accurately and automaticallysteering a torpedo in a direct line by thismeans," and of the Whitehead firm having"produced the apparatus which is fitted toevery torpedo made."

Under the subheading "Automatic CourseStabilization" it is said, " . in 1912, theSperry Gyroscope Company and the U. S.Navy were developing a precise and reliablemotor-driven gyrocompass with remote re-peaters." This development is understood tohave been undertaken by Sperry alone, theNavy adopting the system upon its appear-ance in 1911. The paper continues: "TheHammond Laboratory engineered the modi-fication of one of these devices so that therepeater controlled not a compass indicator,but the operation of a steering engine." Thismodification was rather obvious since theidea of steerinig a ship automatically from amagnetic compass was old. This connectingof a Sperry gyro to a steering gear insteadof to a compass indicator is referred to as the"automatic pilot principle," as if the auto-matic pilot originated with Hammond.

This section of the paper, under the pre-viously mentioned subheading "AutomaticCourse Stabilization," is made more con-fusing by the inclusion in it of a reference to

3The New York Times, p. 11, col. 3; July 24, 1915.4 B. A. Fiske, 'From Midshipman to Rear-

Admiral," The Century Co., New York, N. V., p.232; 1919.

' Footnote I, p. 1192.

three Hammond patents,6 as if these patenitscover course stabilization and the automaticpilot. They do not; they apply only to theapplication thereto of radio control. In fact,the arrangement shown for combining gyroand steering engine is unserviceably crude-the control is intermittenit rather than con-tinuous, through declutching, and there is niomeans for restoring the rudder to normalafter a turn, i.e., repeat back, so niecessaryfor an operable automatic pilot. Thus, thethree patents added nothing to automaticcourse stabilization per se and their inclusionat this point in the text is misleading.

The man who pioneered and producedthe automatic pilot was Elmer A. Sperry.His early progress is described in a compre-hensive paper of 1913. "Perhaps the mostinteresting of all the apparatus which wehave developed is the aeroplane stabilizer,. . . " the section on this subject begins. Itwas applied to a Curtiss Hydroplanie, and ispictured in Figs. 28 and 29.7

Under the subheading "Security ofRadio Control,"' Tesla is credited withhaving "proposed a security system basedupon the coincidental transmission onl twochannels: a forerunner of the 'and' principleof modern computers." But ahead of Tesla,apparently, were the two British inventors,Wilson and Evans, mentioned earlier in thepaper. Their U. S. Patent No. 663,400 of1898-1900, shows coincidental transmissionover two channels. Two short-wave Hertziandipoles disposed mutually perpendicularwith a similar pair for receiving, providetwo channels by polarization. The receivingconitrol electromagnet is made dependentfor its operation upon the receipt of bothchanniels, whereby it appears Tesla waslimited to two different frequencies.

A so-called Hammond system which usesin a conjoint manner the familiar markingand spacing waves of the Poulsen arc tranis-mitter is described,. Later in the paperthis is made the basis of claimiis to FM.But de Forest, then of the Federal TelegraphCompany, who installed Hammonid's arcequipment in 1913, already had devisedwhat he called " . . . a diplex system oftelegraphy, using a high-speed chopper."It "automatically changed the wavelength ofthe transmitter from A to B a great numberof times per second, so that both the A andB operators could dispatch their messages.... "9 Hence the Hammond claim to " . . .the first example of security systems usingboth time and frequency diversity" appearsto have been an adaptation to a slow"secuLrity" operation of de Forest's diplex.

6 Footnote 1, p. 1192, reference 7.7 E. A. Sperry, 'Engineering applications of the

gyroscope," J. Franklin Inst., vol. 175, pp. 447-482;May, 1913.

8 Footnote 1, p. 1193.9 L. de Forest, "Father of Radio; The Auto-

biography of Lee de Forest,' Wilcox and Follett Co.,Chicago, Ill., p. 277; 1950.

1959? i1253

1254

Toward the end of Section I I of thepaper,10 there is quoted a claim from aHammond patent of 1932-1936"1 which issaid to be "the statemiient of the ProximityFuse principle." This is erroneous, for theclaim is for a torpedo, nmeaning in water,from which the energy radiated muist becompressional or sound waves, the only kinddisclosed in the patenit, whereas the proxim-ity fuse employs radio waves.

THE TRIODE TUBE (SECTION III)

The technological revolution that has re-sulted from the electron tube requires thatreports of its onset be rendered correctly.The report given in the paper is from thestandpoint of the Hammond group, andwhile this is a welcome conitribution, it is bynature limited and one-sided, and containissome errors. Hence, additional evidence isoffered as follows.

The second paragraph quotes our oldfriend Robert Marriott as having writtenthat de Forest's Audion "was used to someextent as early as 1906 . . . ". The quotationis correct, but the assumption that it re-ferred to the triode rather than the diode, asof 1906, is in error. It was the two-elementtube that was publicly christened that yearwith the name Audion in de Forest's AIEEpaper of October 20, 1906, devoted to thediode and entitled simply, "The Audion."Incidentally, Pupin amusingly said of thename: "It is a mongrel. It is a Latin wordwith a Greek ending!" And he expresseddissatisfaction with de Forest's inability toexplain its modus operandi.l2 In his recentautobiography, de Forest refers to his de-tector tube as "a carbon filament surroundedby a platinum plate,"'3 which he used inreceiving at 42 Broadway, New York, in1906.

The grid triode appears to have been in-vented toward the very end of that year orthe beginning of 1907. It was filed uponJanuary 29, 1907 and issued as a patentFebruary 18, 1907, No. 879,532, entitled'Improvement in Oscillation Detectors."(There was no time lost in those days!)Just ahead of it de Forest had devisedanother form of triode, one in which thecontrol electrode was a second plate locatedon the side of the filament opposite to theanode. He sought to make of it a telephoneamplifier; but being unable to obtain anmpli-fication, contented himself with filing aspeculative patent application October 25,1906. It was issued January 15, 1907, asNo. 841,387, entitled "Device for Amplify-ing Feeble Electrical Currents." Interest-ingly enough, the patent drawing shows,connected in series with the input control elec-trode, a condenser such as became familiarin the grid audion detector. But whereas inthe grid tube it enhanced the detector ac-tion, it could only do harnm in the amplifier,causing it to block. This probably was onereason for the failure of the two-plate ampli-fier, the other being the lesser electrostaticcontrol of the filament-aniode electroni path.

'° Footnote Io, p. 1197. ."1 Footnote 1, p. 1197, reference 21.12 L. de Forest, "The audion," Proc. AIEE, vol.

25, pp. 719-747; October 20, 1906. Discussion, pp.863-873.

"3 de Forest, op. cit., p. 210.


So, it fell to the grid form of tube to lead theway.

The earliest puiblic disclosuire known tohave been <made of the grid audion detectorwas in a lecttire de Forest gave on March 14,1907, Oil "The Wireless Tranismiission of In-telligenice," before the Brooklyn Inistituteof Arts anid Scienices. It wvas about that timethat the grid atidioni began to come intosomne tise, `btit apparenitly in very smallnuinbers, " as Marriott said. Among thosesmall users, to the writer's knowledge, werea few amateuirs who learnied where the bulbscould be procuired, manaaged to save up therequired $5. anid then suffered the filamentburn-out sooi0 to follow! The writer, withtwo other amiiateurs, Atisten M. Curtis andFrancis A. Hart, had attended de Forest'sBrooklyn lecture and there made the ac-

quiaintance of "Doc" and his young assistantJohn V. L. Hogan. The grid audion detectorconitiniued for some years solely as a detectorwithotit getting very far, as the authors ofthe paper indicate, for it was relatively ex-

pensive and only moderately more sensitivethan the simple crystal-contact detector.

Hammond and Purington are to be con-

gratulated for having at long last ptulledaside the curtain of secrecy and revealedFritz Lowenistein's contribution in makingde Forest's grid audion detector inito aii

amplifier and also ani oscillator. But theydo not tell the whole story and give the im-pression of Hammond's role having beenmore than it was. It was not acttially "as a

consultant of the Hammond Laboratory,"that "Lowenstein on May 11, 1911, under-took in New York the development of thethree element 'ion controller' .. . ". Thedate is that of a letter-contractl4 which de-fined the Hammond-Lowenstein relations,addressed by Hammonid to Lowensteiin andsigned by both, which runs as follows:

Frederick Lowenstein, Esq.,115 Nassau Street,New York City.

NMay 11, 1911.

Dear Mr. Lowenstein:I am writing you a letter to confirm the pOiitS

taken up in our conversation this morning at theHotel Belmont, with Mr. John Hays Hammondand Mr. George Clark. These points, as I recol-lect, are as follows:

You are to work and develop two separateinventions-one, my own automatic wirelessselective system, and the other, your controller.

On account of the development of my wirelessselective system, I agree to advance to you thesum of $1,000.00 for your personal supervision,advice and services in the designing and construic-tion of my invention....

In the second proposition, to develop yourcontroller, I shall advance you the sum of$1,000.00 for the purpose of constructing suchapparatus as may be necessary for experimenta-tion, with a view to perfecting your controller....

(The teriml "controller," or "ion controller,"was Fritz's alias for the name "Audion"which de Forest had bestowed upon Flem-ing's tube upoil adding to it the "B" bat-tery.) The rest of the agreement givesHammond an option to take a 50 per centinterest in the controller invention (whichis understood not to have been exercised).

From the above it is evident that Lowen-steiii was a coilsultanit to Hammond for thelatter's selective radio svstem for torpedo

14 This letter-contract has kindly been made avail-able to the writer by the authors. It was part of areport by E. S. Purington, "Early History of SelectiveReceiving Systems with Special Reference to...Cases of RCA vs Splitdorf Co., and RCA vs GeorgeH. Walker Co.," p. 22; February 19, 1938.

Jutly

control, but not in respect to his oWI 1 iOncontroller. Hammond's relation to Lowen-stein in respect to the ion controller was thatof financial backer, or btnsiness part ner. Thisis borne out by the fact that in applyingfor a patent Lowensteini usecl his own patentattorney; and when he later sold the paitenitto the Anmerican Telephone and TelegraphCompaniy the paymenit, of the famI10ous$150,000, was to him. Fritz had tried thegrid audion as an amplifier before becominigassociated with Hammond. This is indicatedin his letter to Haimmond of September 19,1911, quoted in part in the palper, whereinLowenstein speaks of his "efforts on1 repro-ducing the telephone tests of last winter

,"lo the winter of 1909-1910. What thesetests were, fortunately, has been told byFritz himself in aniother documlent, in anlaffidavit submitted to the Patent Examinierin the course of prosecuting his patenit ap-plication-that which became the famuouisnegative grid, or "C' battery, Patent No.1,231,764 of 1912-1917. IThe affidavit, swornito on September 8, 1915, is to be founld inthe Patent Office record of that patent. Itdescribes how interest was first aroused byan experience in 1906 wherein Lowensteiniobserved the seiisitivity to electrostatic in-fluence of a Cooper-Hewitt merctirv arcrectifier. It theii goes on to say:

In the winter of 1909-1910 I did some work as aconsulting expert to the President of the RadioTelephone Company of Newark, N. J., and intheir shop and at that time I constructed andassembled an operative telephone system of whichthe receiving end was arranged substantially asshown in the drawings of my above application,except that the grid 18 was simply connected toone side of the filament 16, i.e., at the same po-tential as the filament.

Accomipaniyinig the affidavit were ExhibitsA, B, and C. The latter, a reproductioni ofthe patent drawinig, shows a grid Atudionprovided with audio inptit and outptit trails-formers connected as an amplifier in thereceiving leg of a stanidard telephonie suib-scriber inistrumnenit.

'rhe affidavit continues:In 1911 1 did further work oni the inivenitioni in theway of perfecting details thereof.

(i.e., wheni backed by Hamiimond). Theaffidavit theni reveals how Fritz canme tosubstittite for the grid condenser of theaudioni detector the negative "C" batterywhich made of it a class A aiiiplifier, whichnegative grid condition proved to be the in-velntion of the patenit.

The apparatus employed in the 1911 testswere constructed with the aid of Benjamin T.Miessner (now at Purdtue, Indiana), and GeorgeH. Scherff, of New York City.

In a talk in 1911 with Louis Engelhorn at theChicago end of the line, and Harris Hammon-dand myself at the New York end, we employed acondenser in the grid circuit and found that thetalk over the line was poor, the current throughthe controller tending to choke or stop. I foundthat this could be remedied readily by touchingthe grid binding post repeatedly to discharge thegrid and open up the talk. This gave me the ideaof connecting the grid to a point ultranegative inpotential relative to the filament. Such a connec-tion was actually made in the latter part of 1911and was fouind to be a very substantial improve-ment.

TIhese, then, were the steps by whichLowensteini coniverted de Forest's gridaudioni detector to the magic amplifier itbecaml-e:

1s Footnote 1, p. 1198.

Discussion of "A History of Some Foundations of Modern Radio-Electronic Technology"

1) Initial interest in the possibility ofsome form of vacuum tube amplifier,aroused through contact with PeterCooper-Hewitt's mercury arc rectifiertube (a form of which Hewitt himselfwas developing as an amplifier).

2) Familiarity with the Audion grid de-tector, gained while working as a

consultant for de Forest's old RadioTelephone Company, soon defaulted,1909-1910, which led Fritz to try tomake of the audion an audio-frequency amplifier. He seems to havehad some success, but evidently keptit to himself at the time; his obliga-tion to the Company is not known.

3) Renewal of the audion amplifier testsin the fall of 1911 with Hammond'sbacking, resulting in amplified recep-tion of long-distance telephone callsand in the attainment of a true ClassA amplifier by means of the negativegrid discovery.

Therefore, it is seen that Lowenstein was on

the trail of the audion amplifier before be-coming associated with Hammond andcarrying out the "further work on the in-venition in the way of perfecting the detailsthereof." Under these circumstances thepaper is misleading in implying that hestarted the development on May 11, 1911and in the capacity of consultant to theHammond Laboratory.

The Oscillating Audion

It is well established, as the authors say,that Lowenstein had the audion amplifierworking as an oscillator toward the end of1911, and for both audio and radio fre-quencies. The strange thing is that it wasnot followed up, the more so in view ofHammond's high hopes for it as expressedin his letter to Beach Thompson of January25, 1912, given below. And it is singular thatto Hammond, "The exact nature of theionic devices and the manner of operationare not known." One wonders too that theevidence of Lowenstein's having the audionas an oscillation generator during the winterof 1911-1912 was not presenited to thecourts in the long de Forest-Armstronglitigation over the oscillating tube. Such evi-dence would have demonstrated the naturaltendency of an amplifier to oscillate andhence how little invention there was in theoscillating audion per se once it had becomean amplifier. As matters were allowed togo, it fell to others to give to the world theoscillating audion in useful form, mostnotably, perhaps in terms of early date andapplication of control of frequency, toAlexander Meissner of Telefunken'6 using a

gaseous tube of the von Lieben Triode.

An Important TipIn view of its probable importance for

de Forest, then working at Palo Alto, Calif.,for the Federal Telegraph Company, theletter which Hammond wrote the Presidentof that company, and from which theHammong-Purington paper quotes in part,deserves to appear in full:

1I A. Meissner, 'The development of tube trans-mitters by the Telefunken Company," PROC. IRE,vol. 10, pp. 3-23; February, 1922.

January 25, 1911.(Typist's error, should be 1912)

Beach Thompson, Esq.,President, Federal Telegraph Co.,

Merchants Exchange Building,San Francisco, California.

Dear Sir:I have recently been informed about the wire-

less work you have been doing on the PacificCoast, and I am much interested in the resultsthat you have obtained. If you have any descrip-tive matter I would appreciate your sending itto me.

I have been experimenting with a new form ofapparatus designed to produce undamped andhigh frequency oscillations. Our method is farmore reliable and simpler than the Poulsen arcmethod, or the high frequency alternator systemas used by Fessenden and others. We are in proc-ess of developing this apparatus, and when it hasreached a practical point, I would be very glad tosend you more complete information regarding it.

In the experiments we have found that ourmethod is highly suitable for wireless telephony,as there is absolutely no sound produced whatso-ever as in the arc or hf alternator. I believe thattelegraphy by means of undamped high frequencyoscillations is the logical future of this art, for thereasons which you have already discovered andproven: that far better ttuninig may be obtainedwhere there is no decrement to the wave train,and that there is less absorption of energy in longdistance transmission, and also the importantfact that low voltages are used at the transmittingstation. However, the chief weakness in all sys-tems of this kind is essentially in the means ofproducing the continuous high frequency oscilla-tions.

I am quite familiar with the art in Europe andduring my recent trip to Germany found thatmost of the companies had abandoned the arcmethod of oscillation production. It is for thisreason that I believe there is quite a future in thedevelopment of the work which we are carryingon.

Hoping that you will be kind enough to sendme any data which you may be willing to disclose,believe me

JHHJr/TYours very truly,

On the same day Hammond wrote to an

acquaintance of Thompson, and since thisletter, too, is evidence of a stimulative tipgiven the Pacific Coast people, it is presented:

January 25, 1912Major F. R. Burnham

Llankershim BuildingLos Angeles, California.

Dear Major:I want to thank you very much for your letter

in regard to wireless development in California.It certainly is very interesting to me as the re-ports I have had of this enterprise have been verymeagre. I will herewith write Beach Thompson,informing him that the iron controller which yousaw in my experimental laboratory here has re-cently shown some remarkable results in experi-ments in which we produced high frequency un-damped oscillations with far better results thanhave ever been obtained by the Poulsen method.

I hope some day that I will be able to in-troduce a wireless system in Sonora. After theYaqui has developed enough they will need astation there, and we could furnish a good one.

Very sincerely yours,JHHJr/T

(The term "iron controller" is a stenographicslip for "ion controller.")

Photo copy of each of the above letters(from Hammond's file carbon copy) werekindly given the present writer some yearsback by Hammond and Purington. Ap-preciating the probable bearing of themupon de Forest's making the audion into an

amplifier at Palo Alto in the summer of 1912,a copy of the letters was sent to him, withthe question of whether they may not ac-

count for Beach Thompson having askedhim to undertake the further developmentof his audion. Dr. de Forest's response was:

"I do not recall that Beach Thompson evermentioned his correspondence with Ham-mond, but very likely that is what inducedThompson to urge me to develop the audionas an amplifier.""m' Whereby we see that

17 Letter to Dr. L. de Forest to L. Espenschied.September 15, 1953.

Lowenstein, having been indebted to deForest in the first place for the vital gridtube, repaid his obligation through Ham-mond's letter, perhaps tinwittimlgly!

Bell System Side of the Picture

An insight into what was happeninilgwithin the Bell System at the time of theHammond-Lowenstein approach may bewelcome: the American Telephonie anidTelegraph Company and associated WesterniElectric Company already had startedtackling the telephone repeater probleiifrom the standpoint of a vacuum tube ele-ment of some kind. From the University ofChicago laboratory of Prof. Robert A.Millikan a young graduate studenit, Dr.H. D. Arnold, had been recruited. He startedto work at the beginning of 1911 and tookup the kind of vacuum tube that seemiiedlikely to carry the load of a telephonie re-

peater, the mercury-arc tube similar to thatof Peter Cooper-Hewitt. He had succeededin getting amplification when oLir present

story opens.On January 27, 1912, Hammond anid

Lowenstein took to the office of transmissionengineer F. B. Jewett a sealed box and demin-onstrated it as a prospective telephonie re-

peater. Further contact was made in JuLnte,and there were additional telephone coii-

versations, but not until January 12, 1913,while Lowenstein was in Europe, was itfully disclosed what was in the "Black Box."

Meanwhile de Forest himself had suc-

ceeded in making his audion into an ampli-fier on the Pacific Coast, in the stilniumer of1912, and through John Stone-Stonie ap-

proached the American Telephone anidTelegraph Company. De Forest came eastand on October 30 and 31 demonstrated theaudion as an audio amplifier to Dr. Jewettand E. H. Colpitts in the laboratory of theWestern Electric Company, at 463 WestSt., New York. He left the device, and thefollowing day, November 1, Colpitts calledin Arnold and showed it to him. Arnold latertestified frankly as to his impression: " .

when I went into the room and saw thisthing and saw how it worked I was very

much astonished and somewhat chagrinedbecause I had overlooked the wonderfulpossibilities of that third electrode opera-

tion, the grid operation in the auLdion.... Iknew about the de Forest audion in print,but I was wrong in my impression of whatthe de Forest audion might do because I hadnot realized what the grid would do in sucha device."'18

Thereupon Arnold turned from his owni

mercury arc tube to embrace the audion. Asdemonstrated by de Forest it was a remark-ably sensitive but weak and unreliable am-

plifier. It would amplify only at low speechlevels, about 30 db down; at normal levelsit would block and produce noise, for theaudion still had in it the grid condenser ofits radio detecting days! This trouble was

soon overcome and Arnold then addressedhimself to the improvement of the tube it-self. He had recognized from the beginning

18 Arnold-Langmuir high-vacuum tube litigation.Testimony of 1926 in the District Court of the U. S.,District of Delaware, No. 589 and 598. In Equity.General Electric Co., Plaintiff, vs The de ForestRadio Co.. Defendant. Vol. I of six volumes, pp. 554-556.

1959 1255


that the "blue haze" was due to gas andsought better evacuation. The best of thetubes de Forest had left with Western wererepeatedly pushed to the highest platevoltages they would stand to clean up thegas in them. Other tubes were obtained fromthe manufacturer, McCandless; the electri-cal characteristics were measured; an-d bythe end of the year Arnold and his assistantshad a fair mastery of the newcomer. Therewas ordered from Germany the latest typeof vacuum pump (Gaede, molecular); andupon its arrival in April, 1913, Arnoldstarted making his own tubes of high vacuumand greatly improved design.

Thus, the WVesterin Electric Companyengineers were already familiar with theaudion when in January, 1913 Lowenstein's"black box" was opened to them. They hadexpected to find somethinig new, and weredisappointed when there appeared only "theordinary audion" as they reported. Thenegative grid was noted and Colpitts in hisreport mentioned that the questioni of itspotential was to be studied and the companyshould be free to employ any polarization.This point must have seemed minor to hisboss Jewett, for he lost sight of it. An ex-amination of the patent papers submittedby Hammond revealed that the three claimsstood rejected by the Patent Examiner ontwo de Forest patents. The work of theAustro-German von Lieben group was thencoming to attention, on which the Lowen-stein claims were soon to be rejected by thePatent Office. Altogether, the AmericanTelephone and Telegraph Company's pat-tent attorney Lockwood reported, "I do Inotsee that the Lowenstein people really haveanything to sell," and since they were unableto demonstrate to the contrary, the case wasdropped. Btut Lowenstein's patent attorney,M. C. Massie, was persistent and resource-ful. A few years later he managed to get al-lowed claims on the negative grid. Imaginethe surprise of the telephone patent peoplewhen the patent was issued in 1917 withclaims that read on the grid polarization thatthe engineers had found to be necessary andthat was then in use! So, the patent wasbought, quietly, for the very conisiderablesumill of $150,000. Massie told the writerafterward that the company originally couldhave had the patent for $20,000 and he hadfinally boosted the price to $200,000, tocome down to the amounit agreed uponi!

Thereby hanigs a supplemenitary tale toogood not to note. The writer had knownLowenstein as a fellow IREer; had been atthe American Telephone and TelegraphCom1pany's headquarters on radio mattersduring all this time, and had been aware ofcompany contacts with Fritz, but withoutknowing the subject matter. Imagine then,his surprise upon meeting Lowenstein onelunch time in 1918 in the German restaurantbeneath the WVoolworth Building, and beingshown a check to Fritz's order froni theAmerican Telephone and Telegraph Com-pany for the $150,000! To the question ofwhat was it all about, he cheerfully ex-plained, and then observed in his quizzicalway, "And to think, for just a little drybattery!' The appropriate rejoiner wouldhave been, "But in the right place!" Fritzwas so pleased with his accomplishment thathe carried the exhibit, a photostat, arouind

with him to show his friends, as an Indianwould a scalp! Had the writer not knownFritz personally he would have been una-ware of the telephone company's payment,for so unheralded had it been at head-quarters! Inicidenitally, Fritz's insertion ofthe audion amplifier in the receiving branichof his office telephone inl 1911 conistituted thefirst applicationi of that revolutioniary deviceto the Bell System, sub rosa as it was!

The von Lieben GroutpCandor requires that we recall at this

point something of another group of inven-tors whose work with the cathode-ray tubewas contemporary with that in the U. S. andhad been directed from the beginning at theproblenm of the telephone repeater. TheAustrian Robert von Lieben patenited inGermany in 190619 a telephone repeatercomprising a thermionic three-elementbeam-deflectioni tube intended to be of highvacuum. It was scientifically sound but notsuccessful. TIhe inventor, with two associ-ates, Reisz anid Strauss, fell back upon thegaseous, ionlic, type of thermionic tube be-ginning about 1909. In 1910 several formswere patented in Germanxy.20 One of theseused anl initerveniing grid for control andwas applied for in the U. S. on January 30,1911, anid issuLed September 17, 1912, No.1,038,901. It was this patent as well asearlier de Forest audion patents, that wascited against Loweiisteini. Thereby he wasprevented from covering the audion as anamplifier broadly, his invenition reducinig tothe negative grid feature.

While it seems clear that Lowenisteinstarted on his amplifier quest from deForest's audion in 1909-1910, his more suc-cessful renewed pursuit of it in 1911 miiaywell have been stimulated by some knowl-edge of the von Liebeni work having seepedacross the Atlanitic. He is known to havefollowed the German-language literature,and Hammond's visit to Germany in thesummer of 1911 had mnade Hammond "quitefamiliar with the art in Europe" as he wroteThompson. Since Lowenstein did not get theblocking condenser out of the grid circuituntil late in 1911 (by which time the vonLieben group already were in the U. S. Pat-ent Office), he canniiot be credited with hav-ing been the first to have arrived at the gridthermionic amplifier even in the U. S. Buthe was the first with the type of device thatwas to Will out. TFhe initial promise of thevon Lieben mercury-vapor ionic grid tubeproved to be chimerical, for the device waserratic and noisy and did not lead to thefinial answer, the high-vacuum tube. Fortu-nately for de Forest and Lowensteini, theaudion did! Actually, Lowenstein anid Ham-mond, by cominig into the pictuire when theydid, alerting de Forest, anid leading on to thetwo large electrical companies, performled amajor service.

19 German Patent No. 179,807; patented March 4,1906; issued November 19, 1906.

20 German Patent No. 236,716; patented Septem-ber 4, 1910; issued July 11, 1911. Corresponding U. S.Patent No. 1,059,763; applied for January 30, 1911;issued April 22, 1913.

German Patent No. 249,142; patented December20, 1910; issued July 12, 1912. Corresponding U. S.Patent No. 1,038,901; applied for January 30, 1911;issued September 17, 1912.

High- Vacuum TubeSingularly enough, as the paper indicates,

both of these big companies, the AmnericanTelephone and Telegraph Comlpaniy (anld itsassociates of the Bell system), and the Geni-eral Electric Comlpainy, learnled of the audionabout the same time, late October and earlyNovemiber, 1912. Each wenlt inmmediatelyabout the imiprovement of the myster-iouislittle tube, unknowni to the other. Althouighup to that poinit the mode of operationi hadbeen a mystery, and the ttibe was flimiisy,erratic (hardly any two were quite alike),and unable to carry a material load, withina year or so each companiy had mastered thedevice anid was producing a tube character-ized by regularity and reprodtucibility,whereby it became the revolutionarv elec-tronic tool it did. 'Fhe conitribtitioin of thesecompanies was, then, a major one. It fol-lowed from the applicationi of the scientificknowledge of the time to the temperamentallittle tube, first in diagnosing its troubles,and then in applying the remedies: highvacuum and higher voltage, better filanmentemissioni and loniger life, anid circuits prop-erly designed to go with it. No wonider thesetwo great companies locked hornis over thegreat high-vacuum improvement when theGeneral Electric Company sought and ob-tained a patent on it on behalf of Langimiir.Arnold more modestly had regarded hishigh-vacuum tube as an application ofscientific knowledge rather than invention.The contest continued maniy years, withthe Supreme Court finally stistainiing Ar-nold's view. He was giveni credit for haviniganiticipated Langmuir in November, 1912,anid de Forest was recognized to have goniepart way toward the high-vacLuuLM tube e-enearlier without knowing the physics of it.The Langmuir patent was invalidated onthe basis that, ". . . the relationship of thedegree of vacuum within the tuLbe, to ionliza-tionl, and henice to the stability and effec-tiveness of the discharge passing from cath-ode to anode, was known to the art whenLangmuir began his experimenits." The ref-erence cited is a paper by Lilienfield.2' It ispoilited to as having ". . . miiade a comiipleteand explicit disclosure of the essenitials ... '.The decision went oni to recognize that,"Lilienifeld also dedtuced from] miieter readinigsanid stated the 3/2 power relationi of currenitto voltage, as Langmuir later stated it in hispatenit. From this the collcluLsion is iniescap-able that Lilienfeld kniew anid stated, interms which could be understood by thoseskilled in the art, that in a high vacutumii thecurrenit produced is unider conitrol, stable,and reproducible; and, as he emiiployed highvoltages, that higher power lex els of the dis-charge may be obtained . . . '22

To returni more directly to the Hammnilonid-Purinigton paper: it miitmst have beeni earlyNo eTmber, 1912, rather thani "in late Oc-

21 J. E. Lilienfeld, "The conduction of electricity inextreme vacuum," Ann. Phys., vol. 32, no. 9, pp. 673-738; 1910.

22 (664) de Forest Radio Co., Petitioner, vs GeneralElectric Co. (283 U. S. 664-686). Published in Book75, 'Cases Argued and Decided in the Supreme Courtof the United States, October Term, 1930," TheLawyers Cooperative Publishing Co., Rochester,N. V., vol. 131, pp. 1339-1349.

Also reported by W. R. Ballard, "The high vacuumtube comes before the Supreme Court," Bell. Labs.Record, vol. 9, pp. 513-516; July, 1931.

1256 -fluly


tober, " that de Forest was in Gloucester, forhe had gone first to the Bell people and waswith them the last two days of October.23

Fig. 8 of the paper shows a concentricform of vacuum tube structure (with axialfilament surrounded by cylindrical grid andplate), a design attributed to G. WV. Pierce.As if it were new, Hammond referred it tothe General Electric Company as "theproper triode design." But such form of tubewas not new; it was to be seen, along withmeasured E-I characteristics, in a GermanScientific paper.24

MIODERN INTERMEDIATE FREQUENCYCIRCUITRY (SECTION IV)

This section of the paper recounts someinteresting early inventing by Hammond,but by not fully revealing other contempo-rary developments of intermediate fre-quency circuitry, gives the impression ofthat technique having originated largely inHammond. Actually, it started before himand developed without knowledge of his ac-tivity, secret as it was.

In a patent interference Hammond wasawarded a claim which he interprets as giv-ing him "the broad subject matter" of inter-mediate-frequency circuitry.25 The claim isquoted as reading:A carrier wave transmission system comprisingmeans for receiving and detecting the energy ofa modulated wave, means for selecting a com-ponent of said detected energy, and means fordetecting said selected component.

Thus, the claim is for tandem detection-selection-detection. The paper asserts, "Theentire principle of IF selectivity is expressedby the words 'selecting a component' re-gardless of whether the unselected compo-nents were to be utilized otherwise as inmultiplex reception, or were to be discardedas in simplex telephonic reception."

What is disclosed in Hammond PatentNo. 1,491,772 (1912-1924), of which theabove is claim 46? The modulated "carriertranismiiission wave" is simply that of an in-termittent spark discharge of definite groupfrequency. That group frequency is re-covered in the output of a detector, is se-lected and then detected again, down to thesignal frequency. The receiving selectivity isenihanced by tuning to the spark frequencyas well as to the radio frequency.

Now this addition of selecting the sparkfrequency after detection and then rectify-ing it to obtain the signal frequency, was notnew as of 1912. In 1909-1911, the Tele-funiken singing-spark, quenched-gap, systemof wireless telegraphy which contained itwas well known. The receiver comprised: aradio-frequency tuner, a detector, an ampli-fier sharply tuned to the spark frequency ofabout 500 cycles, a second detector, and atelegraph signal recorder. (The tone-fre-quency signals, instead of being rectified,could be read in headphones or on a loud-speaker.) The amplifier element was electro-mechanical, a stretched steel wire tuned tothe spark frequency drove a microphone,and three such elements in tandem made upthe amplifier, highly selective as it was. The

23 Footnote 1, p. 1198.24 0. von Baeyer, "Ueber langsame Kathoden-

strahlen," (Concerning low-velocity cathode rays),Phys. Z., vol. 10, pp. 168-176; March, 1909.

25 Footnote 1, p. 1203.

system was described fully in the Germantechnical press of 1910-1911 and in TheElectrician of London, page 249, Novemiber24, 1911. Sinice Hammond was familiar withGerman developments of the time, he musthave known about it. A transmitting and re-ceiviing set was imported into the U. S. bythe Telefunken Company of America andexhibited and offered for sale at theirquarters in the little tower of the TrinityBuilding at 111 Broadway, New York. Thepresent writer was employed by this Ameri-can subsidiary of the Telefunken Companyin 1909-1910 and helped set up and operatethe apparatus. Among the U. S. militarypeople to whom it was shown was the thenLieutenant G. C. Sweet, U.S.N. What be-canse of this particular set of apparatus isnot known, but other quenched spark setswere sold to the Army and the Navy, andaltogether the system became well-known atthe time. Hence in allowing to Hammond,as of 1924 on the basis of a 1912 application,this claim which reads on the Telefutnkensystem, the Patent Office must have over-looked prior art. In view of it Hamnmoondcannot be credited with originatinig thedouble-detection technique, starting, as itdid, with audio-frequency IF.

Of Alexanderson's 1912 tuned-radio-fre-quency receiving circuit shown in Fig. 12, itis said that if the tubes of the first stage wereall detectors (they being in parallel), "thenthe system would be of the intermediate fre-quency type . . "Y.6 But there was theni iiobasis for calling them detectors; the "if" is apure supposition of the authors, made in thelight of later developments. Hence the claimthat Hammond's October, 1912, conferencewith Alexanderson had "disclosed the ulti-mate selective receiver with double detec-tion . . ." (meaning superheterodyne) im-presses one as unjustified.

XWhile on this matter of Hammond's 1912approach to the double-detection, IF, tech-nique, it is to be observed that the twice-tandem-interrupted kind of spark transmit-ter of Hammond Patents No. 1,491,773 andNo. 1,491,774, is shown in the little book byMiessner where one reads: "Fig. 82 illus-trates a type of transmitter-receiver unitsuggested by the writer in 1911."27

Another claim28 for a "first" must be cor-rected:The intermediate-frequency principle was firstapplied outside the laboratory to the solution of aWorld War I communication problem of highmilitary importance.

The apparatus is said to have been... constructed by the Hammond Laboratoriesin 1917-18,

andDelivered to the U. S. Army at Tours, France,... on October 10, 1918.

Actually, the IF principle had been applied"outside the laboratory" a year earlier herein the U. S. This was the short wave multi-plex radio telephone system developed bythe Western Electric Company, more di-rectly by R. A. Heising, in 1916 and installedon two U. S. battleships. It is described

26 Footnote 1, p. 1201.27 B. F. Miessner, "Radio Dynamics," D. Van

Nostrand Co., Inc., New York, N. Y.; 1916. See ch.17, "A means of obtaining selectivity,' p. 145.

28 Footnote 1, p. 1201.

briefly in the Craft-Colpitts paper oni "Ra-dio Telephony" given before the AIEE on1February 21, 1919. Not only was this aheadof Hammond's military applicatioti, but thetechnique was superior, enabling a pluralityof carrier channels of intermediate frequencytakemi from the wire carrier art, to be cotn-veved over a radio carrier.

Fig. 14 of the paper shows the double-detection circuit of the 1917-1918 HammondChaffee system,.which was covered by twopatents.29 Only one of these patents showsfeedback on the first stage, namely theChaffee one, and it specifically says it is toincrease sensitivity and that the feedbackshould not be allowed to oscillate. Yet theauthors in afterthought say it was "usable"for heterodyne reception, and assert: "Struc-turally, therefore, the receiver was of themost general 'superheterodyne' variety,since both detectors could be, and duringadjustment often were, of an oscillatorynature." Of course both detectors were "ofan oscillatory nature," detection of oscilla-tioIns being their function, anid they wouldeven tend to self-oscillation. But the first de-tector was not used in the self-oscillatingcondition; the Chaffee patent enjoiniedagainist it. Thus, one sees that the authorsuse "weasel words" to give the impressionthey had a true superheterodynie in 1918,whereas they did not.

The first to arrive at the true suLper-heterodyne and apply for a patent oni it, wasone Lucian Levy of Paris. He invented it asa highly selective antistatic receiver in 1917.Soon thereafter E. H. Armstrong learned ofLevy's receiver while in Paris with the AEF,the present writer has learned from Levy.Armstrong's acquaintance with the principlemay have started in New York with theWestern Electric Company before he wentabroad, but his full appreciation of it prob-ably stemmed from Levy more than fromiHammond as the present authors suggest,although he probably knew also of theHammond-Chaffee system. Upon returninlgto the U. S. after the war, Armstrong soughtto exploit the superheterodyne as a meaniisof amnplifying and receiving the higher fre-quencies, and managed to be allowed apatent. But he had nothing new in principleand finally lost to others, mostly to Levy,all the patent claims. In 1919 Levy hadoffered his American rights for sale to theFrench house of the Western Electric Com-pany, namely La Material Telephonique. Inthis way knowledge of his work came to theattention of Bell System engineers. Thevthemselves had evolved the principle of fre-quency step-up-and-down, but so graduallyand generally that they had not appreciatedall its inventive features. But upon learningwhat Levy was patenting they did ap-preciate it as a high-gain, highly-selective,stable receiver, and purchased his Americanpatent application. Prosecution of it in thePatent Office resulted in Levy securing thedefinitive patent in the U. S. to the super-heterodyne as a means of amplifying andselecting, prevailing over several contestants,including Armstrong and Hammond. (PatentNo. 1,734,038 of 1918-1929.) The writer inrecent years asked Levv abouit his inventions

29 Footnote 1, p. 1201, reference 50.

1959 1257


in relation to Hammond. In a letter of June14, 1955, he replied: "Hammond's workswere entirely unknown in France in 1917."

In the year 1920 the present writer, withthe American Telephone and TelegraphCompany, became aware that there wasdeveloping a considerable technique in thestepping of channels up and down in the fre-quency scale through niodulation anid de-nmodulation in conjunction with amplilica-tioIn and frequency selection. He drafted tworeports calling attention to the sittiation.They showed the existence of some fifteenpatent applications internal to the Bell Sys-tem, and some six inventions outside theBell System, those of A. V. T. Day, Ham-mond, Meissner (the German), Levy, Alex-anderson, and Armstrong. Since the BellSystem engineers were early in leadinig intothis technique, a listing of their conitribu-tions will illustrate the evolution that oc-curred quite independently of Hammonid:

1) Homodyne reception, i.e., zero-beatheterodyne, invented by B. W.Kendall in 1915, Patent No. 1,330,471(1915-1920). Used in the trans-oceanic radio telephone tests of thatyear, including the present writer'sreception at Pearl Harbor, T. H.

2) Single-sideband transmission, where-in the carrier is resupplied at the re-ceiving end by a zero-beat oscillator,invented by J. R. Carson in 1915, inconjunction with the same radiotelephone development. Patent No.1,449,382 (1915-1923).

3) A "static" neutralizing systenm re-ceiving on two frequencies, beatingone down, the other up, to a com-mon frequency, for balancing. Es-penschied Patenit No. 1,309,400(1916-1919).

4) Multiplex radio telephony whereinthree intermediate carrier channelsare modulated en-bloc upon a radiocarrier, then demodulated, selected,and finally detected in individualchannels. Installed on two U. S.battleships in 1916-1917, R. A.Heising Patent No. 1,633,100 (1916-1927). This same year B. XV. Kendallpointed out that Heising's multiplexsystem could operate with carriersuppressed, if resupplied at the re-ceiving end by a zero-beat oscillator(recalled to the writer by Heising in1957).

5) World WVar I iiitervenied.6) By the end of 1919, Carl R. Eng-

lund was using at Elberon, N. J., inthe ship-to-shore radio telephone de-velopment, a three-channiel super-heterodyne receiver, according tothe rememibrance of Harald T. Friisand the writer.

7) Superheterodyne receivers were usedon both the ship an4d shore ends ofthe development, 1919-1923. Sys-tein described in paper by NicholsaIid Espenschied.30

8) Double modulation and double de-tection were used in the radio tele-

30 H. W. Nichols and L. Espenschied, "Radio ex-tension of the telephone system to ships at sea,"PROC. IRE, vol. 1. pp. 193-242; June, 1923.

phone link established in 1920 be-tween Catalina Island and the main-land, Califorinia. Carried a superim-posed telegraph channel. (PROCEED-INGS OF THE IRE, December, 1921,and Bell Telephone Quarterlvy, Octo-ber, 1923.)

9) About this same time, 1920, a super-heterodyne receiver was employed torealize sharp selectivity and highgain, in a radio printing telegraph(lemonistration between New York,N. Y. and Cliffwood, N. J., for thedelegates to a preliminlary interiia-tional conference onl electric coin-munications.A'

10) 1922-1923, a superheterodyne fieldstrength measuring set, made port-able by means of loop and "peanut"tubes requiring modest battery. usedin ship-to-shore development, laterin broadcasting.32 Forerunner of the4-A broadcasting receiving set re-ferred to below.

11) 1922-1923, appearance of the firstcommercial superheterodyne de-veloped for broadcast reception, theWestern Electric 4-A. A copy of anengineering report on its develop-ment was given to Dr. Alfred N.Goldsmith of the Radio Corporationof America in October, 1922, and amodel of the receiver itself was givento him a fewx months later for testpurposes. This receiver was so supe-rior to anythinig else available at thetime that it " . . literally gaveElmer E. Bucher and others re-sponsible for RCA sales the jitters,"said Gleason L. Archer in his book,"Big Business and Radio" (1939,page 92).

Thus it is apparent that IF technologycame into being and went into service quiteindependently of Hammond's more secretefforts in the field.

FREQUENCY MODULATION AND RELATEDSYSTEMS (SECTION V)

As the paper indicates, the idea of FMwas of long standing, without meeting muchsuccess until practiced at the higher fre-quencies with a correspoidingly wide fre-quency swing.

A Hammond patent is cited33 whichundertook to transmit radio telegraphy bythe familiar frequency-shift keying of thePoulsen arc while simultaneously modulat-ing both frequencies for telephony. But thearrangement was so crude as to be sub-stantially inoperative: telephone receptionwould suffer key clicks; telegraph receptionin the earphones would experience inter-ference from the telephone channel. Such a"paper patent" can hardly be said to have"established that two independent com-munications could be sent on the sameband... " (in fact de Forest had alreadydone that). Certainly the disclosure of thepatent was not what founded the modern

31 R. A. Heising, J. Franklin Iist., vol. 193, pp.97-101; January, 1922.

32 R. Brown, C. R. Englund, and H. T. Friis,'Radio transmission measurements," PROC. IRE, vol.11, pp. 115-152; April, 1923.

33 Footnote 1. p. 1200, reference 43.

practice of transmitting two chromiinancesignals in color television.

The presentation of the Chaffee trans-mitter of Fig. 16 as part of a "noise-reductionsystem" is misleading since the nioise ittlndertook to reduce was that arising in thetransmitter itself, not that of the trans-ittinig mediuml.

It is appropriate for the authors to recallsomething of how wide-swing FM arose fromthe advance of radio to the higher fre-q tiencies, where the "nattLiral atmosphericdisturbances were of lessened importance."As ttlbe transmiiitters were pushed to thesehigher frequencies (of the order of 50 Imlc),the mlodulationi of a radio telephone trans-mitter tended naturally to swing the fre-qtieilcy. Appearing initially as a fauilt, themaking of a virtue of this effect was a nia tuiralsecond thought. Chaffee of the Bell Tele-phone Laboratories thus sought to titilize itand devised a receiver for an FM svstem.The printed anniouncemiient of a paper34 hewas to give was followed immediately by apress release by Prof. E. H. Armstronig of hisown invention of FM, now so well-knowni.In the public demonstrations made by Arm-strong he compared the high-frequency FMchannel with an ordinary broadcast channiel,giving the impression that all the nioise im-provement was due to his FM system,whereas perhaps half had been bestowed byNature!

Altogether, the attainment of the higherfreqtuencies by means of the vacuuImi tUbewas the primary force in bringing aboutmodern FM, the inventors being those whowere on the stage at the time seeking thenew. No less is the honor owed to those who,through "inspiration and perspiration,"really gave it to the world.

LLOYD ESPENSCHIEDRetired Consultant

99 82nd RoadKew Gardens 15, N. Y

34 J. G. Chaffee, 'The detection of frequencymodulated waves," presented at Washington, D. C.,April, 1935. Published in PROC. IRE, vol. 23, pp. 517-540; May, 1935.

"Application of negative feedback to fre-quency modulated systems," PROC. IRE, vol. 27, pp.317-331; May, 1939.

Rebuttal by John Hays Hammond,Jr. and E. S. Purington*

On February 3, 1958, we received theuncorrected nine-page galley sheets of apaper "Critique of the Hammond-PuringtonPaper Entitled 'A History of Some Fotinda-tions of Modern Radio-Electronic Tech-nology'," by Lloyd Espenschied, a Fellowof the IRE. We appreciate the courtesy ofthe Editorial Board of the PROCEEDINGS inpermitting us to publish this Rebuttal inthe same issue in which the Critiqtie alsoappears.

This Critique contains both materialrelating to and niot relating to that con-

* Received by the IRE, March 31, 1958.

Ju>ly1258

Discussion of "A History of Some Foundations of MAodern Radio-Electronic Technology

tained in our previous paper. We do notchoose to comment upon the extraneousmaterial except when it appears to havean indirect bearing upon our own material.Our critic has long been known to us as amember of the IRE History Committee. Assuch he has been given, in the past, muchmaterial from our files in which he hadexpressed interest by correspondence. Weregret that we did not have the opportunityof commenting upon his present paper be-fore it was presented for publication, andthat we are now compelled to take up valu-able space to clear up matters that couldhax-e been attended to by a continuation ofour personal correspondence. In presentingouir paper, we expected comments in addi-tion to those kindly furnished by the re-viewers of our first submitted draft, and wewould have welcomed constructive criticismof otur effort to establish radio-electronichistory upon a more correct basis.

For purposes of later identification, wewill number the items upon which we wishto comment consecutively in the order ofappearance in the Critique. We will thengive for each item a quotation from theCritique, to assist a reader in locating thematerial to which we are responding. There-Uponl will follow our rebuttal or comment foreach case. At the end of our rebuttal orcomments on all items, we will list suchreferences to published or unpublished ma-terial as may seem appropriate, with refer-enice numbers for each documentation cor-responding to the items to which they per-tain. Moreover, we will be glad to supplycopies of listed unpublished material to theEditor of the PROCEEDINGS, and to theChairman of the IRE History Committee.The items upon which we wish to commentfollow.

I. INTRODUCTION

1) Critique. " . . . the roots of our moderntechnology trace back generally to sourcesother than the Hammond Laboratory."

Comment. Many of the roots that nour-ished the work of the Hammond group andits contemporaries were recorded in ourpaper: the pioneering work of Wilson andEvans, Tesla, Shoemaker, in basic radio-dynamics; of Edison, Fleming, De Forest inbasic electronics; of Tesla and Fessendenleading to the development of basic inter-mediate frequency circuitry; and the initialthinking of Gueroult, Taylor, Helmholtz,Ehret in the field of frequency modulation.The later work of the Hammond group andof its contemporaries in these four fieldshas been set forth on the basis of our bestknowledge.

2. Critique. "Hammond's work was con-ducted in secret, as the authors aver, ...."

Rebuttal. Hammond's early work forradiodynamics was conducted in secret inthe same sense that the Manhattan Projectin atomic energy was conducted in secret.It was not kept from the military, for exam-ple, but parts of the work were kept fromCongress by the military. All that we averredwas that "publication of technical and his-torical information was highly limited bygovernmental and self-imposed restrictions."The governmental restrictions were mainlyby act of Congress requiring certain patentapplications to be placed in the secret

archives of the Patent Office, as set forth inthe paper. Self-imposed restrictions were forthe purpose of observing the proprieties andkeeping faith with officials who expressedtheir convictions very freeely in defensematters. In this rebuttal, we are lifting aself-imposed restriction in one matter, be-cause we know the officials quoted wouldso desire it under the present circumstances.

Radio-electronic work mainly of defenseinterest has always been either developedin close cooperation with the military, orin the initial stages has been brought to theattention of the proper Governmentalauthorities. Radio-electronic work mainlyof commercial interest has had a properoutlet to the industry through conferences,demonstrations, and patent arrangements.For example, consider the early work leadingup to intermediate frequency circuitry. InFebruary, 1912, even before the filing of apatent application, information of militaryand commercial value was given both toB. F. Miessner, temporarily of the Lowen-stein-Hammond laboratory, and to Dr.L. W. Austin of the Navy Department.Thus in a Miessner letter1: "Mr. Lowensteinhad kindly loaned me your letters to himconcerning the new selective system. Coni-trary to my usual custom, I believe theinvention a good one. It, at least, is a verygood way of dodging the Tesla and Fessen-den patents...." The mnanner of referringto the Tesla and Fessenden contributions,of course, was not the way that Hammondhad put the matter, but serves to identify2the material under discussion. Also, in alater letter3: "I am glad to learn what Dr.Austin thinks about your new selective sys-tem and the probability of its being applica-able for commercial as well as tel-automaticwork. Kindly accept my thanks for theletter. I believe that by being in touch asclosely as possible with all phases of the workI can tackle my part of it in the properway. "

Thus there was no improper holding backof information, either froin a top levelGovernment expert, or from a technician ofa subsidiary laboratory.

II. THE RADIODYNAMIC TORPEDO

3) Critique. " ... but singularly omittedfrom mention is the one who received fromthe Patent Office the uLnderlying claims, .... "

Rebuttal. The claim cited is not an under-lying claim because of the clause "as setforth," without which the claim would prob-ably not have been allowed, since it wouldthen have read upon the wire-controlledtorpedo covered by patents long since ex-pired. A very similar claim, also with therestriction "as set forth," is in the Teslapatent, our previous footnote 2, as follows:

"5. The combination with a source ofelectrical waves or disturbances of a movingvessel or vehicle, and mechanism thereon forpropelling, steering or operating the same,and controlling apparatus adapted to beactuated by the influence of said waves or

I B. F. Miessner to Hammond, February 6, 1912.2 Disclosure of Hammond, leading to U. S. Patents

X,522,882 and 1,491,772.3 B. F. Meissner to Hammond, February 12. 1912.

disturbances at a distance from the source,as set forth." Neither the cited Fiske norTesla claims were infringed by Hammond inhis 1914 Natalia installation, because of the"as set forth" clauses. WVilson and Evans,with a December 29, 1897, British filing date,very probably had an effective date of in-vention prior to both Tesla and Fiske. Theprecise reason that Fiske was not named byus as a pioneer is because of our unider-standing that from a chonological standpointWilson and Evans preceded him, and froma practical standpoinit of experimentaldemonstration, Wilson and Evans andTesla built radiodynamic models controlledfrom a distance. In the latter years of theireffectiveness, the Fiske patenits were owined4by the Western Electric Company. Pre-sumably because of the response to the citedHammond letter, it was regretfully enteredinto the record5: "I was informed that thepatent was never developed into an operat-ing machine." Fiske's works in Navy fieldssuch as range-finders and torpedo-planeswere much admired by Hammond, but noteven personal friendship would be a reasonfor naming him as a pioneer in the field ofradiodynamics.

4) Critique. "In the summer of 1915,Hammond was selling to a Congress worriedby the European War then raging, his sys-tem of wireless control of torpedoes."

Rebuttal. This is a gross exaggeration.In March of 1915, the approach to Con-gress was not by Hammond but by Secretaryof War Garrison6 who urged that the Ham-mond inventions be given favorable con-sideration. But the Congressional leadersconsidered it then too late to enter thematter on the agenda for that session.General Weaver, Chief of Coast Artillery,then advised Hammond that if he so desired,he could now take his inventions to a bettermarket abroad (as Hiram Maxim had donie),without deserving any censure at home.Mr. Hammond elected to await the niextsession of Congress, and the FortificationsCommittee of the House held early hearingsfrom January 24 to February 10, 1916.Both the Army and the Navy experts re-ported very favorably in a hundred pagesof printed record, our previous footnote 14.

Even in the summer of 1916, Congresswas not worried about the war, as long as itraged only in Europe. Its concern was thatsooner or later there would be a winner ofthat war, and that foreign battleships mighteventually appear off our coasts to bombardour cities. The Hammond invention was ofgreat interest because it promised a methodof sending a powerful guided missile out tosea under precision control from an aero-plane, much farther than was possible withthe ballistic missiles from coast defenseguns. Senator Townsend of Michigan7 ex-pressed it concisely: "Now it seems to methat in these uncertain times, in thesetimes when we are preparing for defensivewar, the United States Governmnent cannot

4 Congressional Record, 64th Congress, 1st Ses-sion, p. 10875, col. 1; June 13, 1916.

5 J. H. Hammond, Jr., "Telautomatics," vol. 2,p. 35; 1910-1912. Copy available in Navy Dept.Library.

6 Congressional Record, 64th Congress, 1st Ses-sion, p. 11785, col. 1; June 30, 1916.

Ibid., p. 11667, cot. 2; June 28, 1916.

1959 1259


afford to neglect ani opportunity of thiskind." The leisurely debate appears in thethirty-three pages of the CongressionalRecord in which the matter is covered, overthe period June 13 to June 30, 1916. Mem-bers of Congress were quite unanimouslywilling to make the initial appropriation of$30,000 by which a Board of six Army andNavy officers was expected to find whetherthe guided missile principles developed byHammond would be of benefit to the coun-try. The debate in the Senate was mainlywhether the Board should be required toreport back to a later session of Congress,or should immediately be provided with con-ditional funds so that it would be able toproceed without delay if it considered theinventionAs worth adopting into service.

One of those who may have looked be-yond the immediate horizon was SenatorStone of Missoutri, who spoke8 as follows:

"What is claimed for it? What will it do?In a word, this is what it is claimed it willdo, namely, that through the operation ofelectrical energies controlled by the devicesof this invention, an explosive body may bedirected in its course until it comes in con-tact with a given body, stationary or mova-ble, against which it is directed."

Are we not now, forty-two years later,seeking a device to do just that, with thebody against which it may be directed nota battleship twenty-five miles offshore, buta ballistic missile fromii across the entireocean?

The lack of real concern for the warraging in Europe, even as late as ten monthsbefore our entry into it, is shown by the dis-cussion8 as to where a plane was to be hadso that the Board could make the guidancetests of the Hammond torpedo:

Senator Brandegee: "Mr. President, Iwas going to ask the Senator this question:Inasmuch as the House provision providesfor a Board of Army and Navy experts tomake whatever tests they think ought to bemade, and to report upon this purchase-and the machine cannot be bought unlessthey should report favorably-and inasmuchas the Government owns an aeroplane forits Army, officers and aviators can operateand make the test without any expense atall, without purchasing an airship, why doesnot that fulfill the conditions?"

Senator Lane: "I do not think thisGovernment owns an aeroplane which willtravel through the air with any safety to thenavigator: in fact, most of them have cometo earth and caused a loss of life of the helms-man. I think we are practically out of aero-planes: at least, I ani so informed, althoughwe have spent millions of dollars in buildingthem. We ought, however, to build anothertype, and we should do so promptly."

Seniator Brandegee: "I will say to theSenator from Oregon that I saw a very good-looking aeroplane the other day over at theSenate Office Building-it was a Curtissmachine, I believe, or a Wright machine-which the Goverinment, I suppose, canpurchase, if it so desires, for a very moderatesum. Aeroplanes, as I am advised, cost fromabout $7500 to $100,000, according to sizeand depending on the kind desired."

8 Ibid., p. 11795, col. 2; June 30, 1916.9 Ibid., p. 11789, col. 1; June 30, 1916.

Senator Lane: "I also saw the aeroplaneto which the Senator from Connecticutrefers. It was in a good, safe position; itwas near the ground, and I climbed aboardof it."

Congress was not too concerned aboutthe war raging in Europe, even as late asthe summer of 1916. It was not until afterthe election of November, 1916, that thecountry realized that such slogans as "Weare too proud to fight" and "He kept us outof war," had contributed to bringing aboutthe worries of Congress in the summer of1917.

Acttually, in the summer of 1915, whilewaiting for another session of Congress,Hammond was busy'0 with other activitiesrelating to the firing of standard navaltorpedoes. In a letter of August 23, 1915,Captain XV. S. Sims, Comniander, DestroyerSqtiadron, Atlantic Fleet, advised the Secre-tary of the Navy: "NMr. John Hays Ham-mond, Jr., is the inventor of an applianceto facilitate the fire control of torpedoes.He has explained the principle of the devicebefore the Destroyer Squadron Commanderand the Squadron Torpedo Officer, Lieu-tenant Commander J. V. Babcock, and inour opinion the device merits the Depart-ment's serious consideration.... It is there-fore strongly recommended that Mr. Ham-mond be given every opportunity and facilityto prosecute his experiments." Naval Ord-nance then financed the work, equipmentwas built by the Cummings MachineWorks in Boston under the supervision ofA. D. Trenor of the Hammond group, andthe system is a fundamental method of tor-pedo firing.

5) Critique. "Two World Wars have nowoccurred with no military use of the radio-controlled torpedo; it is just as well exceptfor the futile expenditure of technical effortand public money."

Rebuttal. The first part of this statementis in error, since the meaning of "torpedo"given in the opening sentences of the sectionis sanctioned by Congressional and militaryusage. Most certainly, the inventions ac-quired by the Government cover applica-tions to both water-surface torpedoes andaerial torpedoes, as well as to the under-water torpedo by which the principles ofmissile guidance were required to be demon-strated. The "Azon" bombs of World WarII"l and the "Glider" bombs'2 used by theU. S. Air Force in wrecking the railroadyards of Cologne are examples of "aerialtorpedoes" operatintg by the Hammond meth-od. The "Stingray" boats used against theJapanese and the drone-boats used againstthe Germans'3 are examples of radio-con-trolled water-surface torpedoes. The Ham-mond work with underwater torpedoesterminated successfully in 1931, and anyfailure to use them in World War II is notchargeable to Hammond. When the U. S.Congress failed to consider the 1915 recom-mendations of Secretary of War Garrison,Hammond was released by General Weaverfrom any moral obligation to deal further

IOU. S. Patents 1,388,640; 1,431,140; 1,431,141;1,431,142; and 1,431,143 to J. H. Hammond, Jr.

11 J. C. Boyce, "New Weapons for Air Warfare,"Little, Brown and Co., Boston, Mass., pp. 225-235;1947.

12 U. S. Patent 1,818,708 to J. H. Hammond, Jr.'3 Authors' previous paper, p. 1192.

with the U. S. Government, and there wereoffers from abroad to take over the inven-tions and devices of the Hammond Labora-tory. If Hammond had not elected to con-tinue with the Congress in 1916, it is quitelikely that water-surface torpedoes WOUldhave been used in Europe during WorldWar I. As it was, the Germans actually didsink a British warship by a surface torpedounder wire control from a shore station.'4

As to the latter part of the quoted seni-tence, we assume that what our critic meanitwas that the technical effort and the publicmoney spent were futile. This is also inerror. The same principles of guidaiice thatwere developed for underwater torpedoeswere also applicable to the conitrol of targetships and airborne target tlroioes. 'I'hisHammond contribution alonie has beeni con-sidered by experts'6 to hax e justih-ledl thefull cost of the Hamnln4ond effort to theGovernment.

6) Critique. "Among the principlesclaimed to have been developed in the 1910-1914 period is that of the automatic stabi-lization of the coturse of a torpedo by meansof a gyro."

Rebuttal. No such claim was ever made.We stated as background of the modernprinciples of missile guidance: "In the ab-sence of a control signal, the torpedo shouldbe stabilized as to course by mechaniismiiswithin itself." For the purpose of disclain3iingautomatic stabilization of the couirse of atorpedo per se, and also of disclainiing anypart of the development of the miotor-driven gyro, we specifically stated: "Couirsestabilization had been practiced in navaltorpedoes by a gyroscope energized only atthe start of a run. But in 1912, . I'l he"had been," therefore, very clearly refers toa timle prior to 1912, which by our footniote7 was the date of the initial Hammond coIn-cept of the use of a gyro in suirface boat con-trol work. Our critic may be suire that ifgyro stabilization of the course of a torpedoby itself had been a Hammonid invention,we would have used the simple past tensewas instead of the pluperfect "had been'";furthermore, we would have giveni a patentnumber as a footnote. Our critic chooses toread by Hammond into the text after theword "practiced," where nio suich insertionwas intended or justifiable.

7) Critique. "This development is tinder-stood to have been undertaken by Sperryalone, the Navy adopting the systenm tiponits appearance in 1911."

Rebuttal. Gyro-compass equipnment wasinstalled upon the Utah, the 1W7yoming anidthe North Dakota in the latter half of 1912.On the basis of Navy reports up to March31, 1913, we considered the work done bythe Navy, especially by Chief ElectricianEngland of the Utah and Ensigni H. R.Saunders of the Wyoming, of sufficienit im-portance to compel mention of the Navy asa party to eveii the technical developmentof the gyro-compass prior to its adaptationby Hammond for radio-control and otherwork in the winter of 1913-1914. If we hadfailed to mention the Navy, we would

14 Letter of Admiral W. S. Sims to Hammond,November 3, 1917.

16 Letter of Admiral W. V. Pratt, CNO to JAG,January 24, 1931.

1260 Jitly

Discutssion of "A History of Some Foutndations of AModern Radio-Electronic Technology"

possibly have been criticized from anothersource.

8) Critique. "This modificationi wasrather obvious since the idea of steering aship automatically fronm a magnetic compasswas old."

Rebuttal. We were writing about enigi-neering, not about ideas. Our critic, as inmany othler instances, fails to cite any refer-ence by which one may judge whether theengineering was along new anid useful linies.The idea of anl antiballistic missile is alsoold, but a tremendous amouniit of inventiveresearch and development is necessary be-fore the idea gets to the engineering stage,for the modern applicationi.

9) Critique. " . . . as if the aLutomaticpilot originated with Hammond."

Rebuttal. Many might consider the gyro-equipnment of a naval torpedo to exemplifyanl "automatic pilot." Certainly Chandler,previous footnote 16, has stated, " . . . wemust regard the gyroscope as the compassof the torpedo as well as its pilot." But cer-tainly it is the function of a pilot to changethe course of a craft durinig a run, and thedevices of naval torpedos did not providefor that functioning. And the Sperry gyro-compass mechanism did not provide for aconnection with the steering engine. We didnot emphasize the Hammonid contributionto the complete automatic pilot system nowused in the navigationi of surface vessels andaircraft, since we were concerned mainlywith radio-electronics. Now that the issuehas been raised, we consider that the officialsof the Government inivolved would approvethe lifting of a "self-imposed restriction"and the release of a part of the transcript'sof a high-level conference of 1916 in whichthe Hammond contribution was discussed.

"Mr. Hammond: I think that there isperhaps another use which might be of con-siderable value. I have been in touch withMr. Sperry about the proposition, and thatis the gyroscope control of these boats. Wehave demonstrated, of course, that thesteerinig is entirely automatic under thecontrol of the gyro-compass, and it is veryaccurate, in fact a great deal more accuratethan any quartermaster would be. In veryheavy weather off Gloucester in a fifty-footboat, we found that a deviation of our courseon a compass was very small and better thanany of the quartermasters could hold thecourse, and that even with suLdden move-ments of large waves, that the mechanismresponded so rapidly as not to allow theboat to be thrown off the course. It seemsthat that might have a very valuable appli-cation in the future, in the steering of shipsin line, and in the steering of submarines,and in the steering of transatlantic vesselsto maintain a more accurate course. Themechanism is foolproof, so far as we havebeen able to find it. Colonel Devine hasobserved its action for a number of miles.

"Mr. Sherley: What do you gentlemensay as to the value of that, assuming thatcontrol is such as has been indicated?

"Rear Admiral Fiske: That is a very oldsubject, that question of automatic steeringof ships, and there are all sorts of opinions

16 "Informal Conference on the Hammond Radio-dynamic System for the Control of Torpedoes,'WVashington, D. C., pp. 15-20; February 9, 1916.

upon it. Some people thinkl it is highly de-sirable to have ships steered automatically,and I am of that impressioni myself, pro-vided, of course, that the apparatus is ofsuch character that the helmsnman, if he wasthere, in case of danger of collision, couldassume control. If there was danger ofcollision, for instance, you would not wantthe ship to be steered automatically if aship were coming across the bow.

"Mr. Sherley: Admiral, what have youto say about that?

"Rear Admniral Benson: I agree withAdmiral Fiske, that if you always have aman there. There is always this element ofdanger if you have something running auto-matically yout are very apt to trust too muchto it and take too much risk, but the prin-ciple, of course, is absoltutely correct. If youhave something that is automatic, that canbe changed instantly, of course it is verydesirable. The only possible danger couldbe the fact you trust too much to it andleave it.

"General Weaver: I would like to askMr. Hammond if it can't be changed in-stan tly.

"Mr. Hammond: It canl be changed in-stantly, because in our work we have a manon the lookout so as to avoid runniing downtargets when we are attempting to hit them,and also to get around the marine laws,because I do not know that it is permissiblefor vessels to travel withouit a crew adlibitum around harbors. We have found incases of such emergency that by the merepressure of a key the gyro-control is dis-conniected entirely and the control comesunder the hand of the man himself. That is,instantaneous.

. . . . . . . . . . .

"Captain Bullard: In this system thatyou speak of, which is your system, you onlyimpress the energy on it wheni you want tochange course?

"Mr. Hammond: Exactly."Captain Bullard: Otherwise you are set

onl a given course and the gyro holds itthere.

"Mr. Hamnmond: Exactly.. . . . . . . . . .

"Lieutenant Decker: I might be able tosay something there. I have seen consider-able service in the Navy and am quitefamiliar with ordinary steering apparatus oniboard a battleship. From what I know ofthe Hammond system and the system usedby the Navy, I see no reason to believe thatthis system could not be applied to theordinary steering apparatus as installedupon the ordinary battleship, and so ar-ranged that the control could pass from thegyroscope or automatic steering device overto either an electrical device that is con-trolled by hand, or to the ordinary systemas at present installed. In other words, theconnection between the gyroscope controland the ordinary control is so flexible thatit could be changed instantly, with the merethrowing of a switch or depression of a key. "

Five years later, Admiral Bullard was incharge of the installation on the target shipIowa, which to our best knowledge was thefirst capital ship to be fitted with automaticpilot equipment. The gyroscope was sup-plied by Sperry, and the linkage to the

rudder was by the Hammon-d Laboratoryand the General Electric Company. TheNavy report17 states that the equipment"will keep vessel on a steady course and isreliable. The instrument will prove of greatvalue in any experiment or operation wherevessel must maintain a steady course. It isan expert Helmsman."

The Hammond contribution, therefore,was not in the development of automaticcourse stabilization per se, nor was it in thedevelopmnent of a continuously-runninggyroscope. His contribution was to themechanisms for shifting the course that wasstabilized by the gyro, and for switching thesystem from automatic to manual steering.This point of view is substantiated by someof the patent claims in the three co-filed andco-issued patents cited. Thus typicallybroad claim 54 of patent 1,418,788 is per-tinent:

"TIhe combination with a movable body,of nieans automatically operative to stabi-lize said body with respect to a given axis,and means to modify the automatic opera-tion of said stabilizing means and to rotatesaid body selectively in either directionabout said axis."

10) Critique. " as if these patentscover course stabilization and the automaticpilot. They do not: they apply only to theapplication thereto of radio control."

Rebuttal. This statement is in error.There are more than ten claims such as thatjust quoted in which radiant energy is notmentioned. The patents cover change of thestabilized course by manual as well as byremote radiant energy control.

11) Critique. " . . . the arrangementshown... is unserviceably crude."

Rebuttal. The word "unserviceably" ishighly improper. The patents were cited tosupport the antecedent statement and toprovide a readily-available reference to thebasic ideas of this new art. The referencewas in a footnote because the techniqueswere mainly not radio-electronic. As thepatents were co-issued, our critic shouldhave at least examined the patents 1,418,789and 1,418,791 with arrangements more in ac-cordance with our description of the Nataliainstallation, using patented and unpatentedimprovements. Anyone familiar with thehistory of inventions knows that practicallyall important basic patents show deviceswhich years later would be considered crude.The Telephone Company itself developedfrom the capital value inherent in the crudedevice shown in the Bell patent applicationof February 14, 1876. But the fact that suchdevices are considered to be "new and tise-ful" by the experts of the Patent Office is thebest nontechnical evidence that they werenot "unserviceably" crude. Note that ourcritic is not only challenging the conclusionsof our own Patent Office, but also the ex-perts who permitted the issuance of the cor-responding European patents: French 474,-906; British 16,328; German 348,277. Itshould be noted that this was a period inwhich even Army and Navy officers retainedpersonal rights even in defense-connectedinventions. Actually, these Hammond ap-

17 "Special Radio Report, Radio Design ProblemNo. 70, Radio and Sonodynamic Control," U.SS.OHIO, p. 8; September 20, 1920.

1959 1261


plications were filed when, as a civilian, hewas workiing informally with the U. S.Government represented at Gloucester byCaptain F. J. Behr, anid they were drawnwith a X iew of conserving the persoiial rightsof the iniventor without disclosinig the enigi-nleerinig details niecessary for the construc-tioin of a militarily-acceptable inistallation.

TFhe degree of engineering perfectioni ob-tained by the end of the year 1914 is coveredby the followinig8 ptublic record:

"Lieutenianit Decker: On this trip wemet MNr. Hammiionid in Bostoni. 'Fhat was thelatter part of November, 1914. Tfhe Natalia,the boat oln which the inistallationi was atthat time, Was lyinig at the wharf at the.Navy Yard at Bostoii.... Fromi the NavyYard we got Lunider way, wenit out of Boston1 larbor uLnlder the control steerinig ap-paratus, and after we rounded the headlandsouitside of the harbor, we set a course forGloucester. 'I'he boat was allowed to steeritself in order to test out the reliability ofthe steering mechanism. The steering mnech-animiism performed as nearly perfect asainything could perform. There was not theslightest hitch, anid at all timiies it fuLnlctionedproperly anid kept the boat on the prede-termined couLrse. I should estimate we ran adistance of something like 15 miles fromii theerrtrance to Boston Harbor up to a light-house off The Graves, and during that timiiethe boat was not touched, as I remember it,and we did not miss that lighthouse in this15-mile run more than about a quarter ofa mile.... As we enitered the harbor ofGloucester, the observer on shore saw us. Weset the boat for shore control, and the opera-tor on shore made uis perform various fancycurves over the harbor and steer arounid afew spar buoys. DuLring the whole of thetest, while I was on the boat, I did not see asingle thing go wrong that would in aniy wayhave disabled the boat or taken it away fromthe control of the operator."

12) Critique. "The man who pioneered,and produced, the automatic pilot, wasElmer A. Sperry."

Rebuttal. This is in error. Any devicewhich can conceivably be termed an "auto-nmatic pilot" must be one which has to dowith steering, since without the word "atuto-nmatic, " a pilot is'9 "the steersmani of a ship;that onie of a ship's crew who has charge ofthe helm and the ship's course." Our critichas cited the "aeroplane stabilizer" de-veloped in 1913-1914 to stupport his state-ment that Sperry pioneered the "automaticpilot." But he failed to observe that theSperry device did not stabilize the course ofthe aeroplane, but functioned solely tomain-tain the plane at a suitable small anglewith the horizon while the course of theplane was steered by a human pilot.

By attemptinig to set up Sperry as thepioneer, our critic niow concedes that Obryand Whitehead who developed the coursestabilizer for naval torpedoes did not therebypioneer the "automatic pilot," presutmablybecause the device was neither continuouslyrunjninig nior alterable during the run. Like-wise, he concedes that whoever conceivedthe idea of uising a magnetic compass as a

18 Our previous paper, footnote 6.'9 The Century Dictionary, The Century Co., New

York, N. V.; 1914.

course stabilizer was not a pioneer, pre-sumably due to lack of reduction to practiceor to lack of practical utility. XXVith these twopossibilities thus excluded, the pionieer inthe field of atutomatic pilot systems was notSperry; it was Hammond. The device of theNatalia (leveloped in 1913-1914 providedfor atitomatic course stabilization betweenthe controls of the stabilized course, andprovided for changing the coturse manutiallyas well as by remiiote radiant enlergy signials.It was the truie prototype of the automiiaticpilot system comiimercialized ten years laterby the Sperry Gyroscope Company for thesteering of large ships, technically knowni asthe "Gyro-pilot," buit more generallytermed the "Metal-Mike."

Sperry's uniiquLestionably basic contribu-tion to many fields of application20 was hisdevelopment of the motor-driven gyroscope.In 1911, he successfully demonstrated hisfirst experimental gyro-comiipass on thetV.S.S. Delaware, leading to the develop-menit of an improved gyro-compass use(d byall Allied Navies in World War 1. Also in1911, he was working tipon the problem ofreducing the roll of ships, and cooperatedwith the Navy in producing equiipment tusedexperimentally on the U.S.S. Worden. As of1927, the largest gyroscope installed for shipstabilization purposes was oni the Japaneseairplane carrier Hosho, reducing the roll bya factor of about eight. In 1913-1914, withhis soin Lawrence and the Curtiss Company,he developed a special gyroscope systemi forreduction of roll and for the automaticbalancing of aeroplanes. With demonstra-tions in, the summer of 1914 in France, theyounger Sperry and "The Sperry Gyro-scopic Stabilizer"'" woi the $10,000 prize inthe "Concours pour la Securite en Aero-planes." These three Sperry developmentsof the Gyro-Compass, the Gyroscopic ShipStabilizer, and the Gyroscopic AeroplaneStabilizer, were of utmost importance. Butthey were not automatic pilots, for thesimlple reason that in all three cases, thecoturse of the craft was held and was changedonily by a human pilot.

Hammond's first business contact withthe Sperry Gyroscope Company was inJuLly, 1913, in the same month that Ham-mlond filed applications for the three patenitsbasic to all automatic course stabilization,either by radiant energy or with manual con-trol of the stabilized course. Sperry suLppliedspecial gyro-compass type equipment speci-fied in a coiitract with Hammnond dated Sep-tember 8, 1913; this equipment was success-fully installed by Hammond and his staff inthe Natalia and operated in an autonmaticpilot system over a distance ruin on March25, 1914. After this pionieer work, followedby the U.S.S. Iowa installation of 1921, theSperry "Gyro-pilot" began to be manu-factured and sold in considerable numibers.In 1925, after an installation on the Levia-than and a patent interference with Ham-mond, the attorneys of the Sperry Gyro-scope Company could cite no prior Sperryart that would dominate the gyro-pilotclaims of Hammond in the then-issued

20 "E. A. Sperry, John Fritz Medalist for 1927,"ASME Meeting, New York, N. Y.; December 7,1926.

21 L. B. Sperry, 'The Sperry Gyroscopic Stabi-lizer,' Flying, pp. 197-220; Auguist, 1914.

patents resulting from the 1913 filings. Pre-sumllably since these patents were in effectexclusively optioned to the U. S. Govern-ment, the nmatter was not pressed and theGovernment received the still-active gyro-pilot rights as an added -dIne in its pswr-chase agreemiienit of 1932.

FExcept for supplvilng gyro equipmenit toHammllloInd in 1913, Sperry was not seriouslyinivolved in auitomatic pilotiiig uinitil aboutAuigust 16, 1915, when he filed for a patent1,446,276 oni an electrically-sustainedazimuth gyroscope. About a hunldred ofthese devices were sold to the U. S. Navy fornaval torpedo work. Sperry's (lifficuiltieswith the auton-matic stabilizer for aeroplaneswere such that he did not give early seriouisthouLght to the "aerial torpedo" or the "ra-dio-controlled aeroplane" requiring coursestabilization. Disturbed by the problems ofradio receptioni in a plane, in which field hehad niot beeni concerned, Sperry botughtrights Lunder a Duibilier applicatioii of July10, 1916, later patent 1,383,177. As theChairmlan of the Committee oni Aeron1auticsof the Naval Consulting Board, Sperry onlApril 11, 191722 reported upon "the wholeAerial Torpedo proposition," and within afew days was ordered to proceed to constructAerial Torpedoes capable of carrying 1000pouinds of explosives. By act of Congress,two classes of torpedoes were to be de-veloped, the completely automatic type anidthe wireless-controlled type. Abouit a hunti-dred test shots were made before the Arm is-tice, at which time quantity prodtictioni had,been started.

Despite this intense effort stustainiedthroughout the twenty months of WorldWar 1, the information concerning the les-sons learned did not, apparently, penetratedown to Army and Navy workers in radiocontrol of aeroplanes in the early post-warperiod. Early work by the Air Service of theArmy was carried ouit in 1920 under thedirect supervision of Lieutenanit R. F.Vaughan, and literally started from theground up. Hammond contributed to thisdevelopment by supplying22 security-typeequipment "with a view of usinig it in co(i-nection with the control of airplanies byradio, the noninterferable characteristicsbeing especially valuable for this worl-."Tests proved the selectivity and se( re(-vfeattires of the equipment, and that conltrolup to 40 miles was possible fromii a grounjidtranismitter. It is noteworthy that inl theirearly post-war work, both the Army and theNavy were hopeftul of successful aeroplanecontrol either with nio special automiaticstabilizer, or withouit the uise of a gyroscope.

I n this post-war period, patent in]ter-ferences developed in the held of aeroplaniecontrol by radio, mainly between the Sperryapplication 207,786 filed December 18, 1917to cover his wartime aerial torpedo work,and two Hammond patents pending basedipon applications of 1914 and 1915 restiltingin patents 1,568,972 and 1,568,974 issuedsubsequent to the interference. As a resuilt,Hammond received the priority, anid sincehis Government obligations were solely in

"2 Deposition of E. A. Sperry, U. S. Patent OfficeInterferences 47,032 and 47,883, p. 44; May 3, 1923.

u Contracts 245 and 358, Engrg. Div., Air Service,McCook Field, Dayton, Ohio.

1262 July


waterborne carriers of explosives, Hammondwas able to grant Sperry an exclusive licensefor developing the airborne field underclaims dominating the change of course of anaeroplane under radiant energy control, suchas the following from patent 1,568,974:

"29. In combination, a self-stabilizing,self-steering aircraft, and means comprisinga radiant energy transmission system forcausinig said aircraft to make any desiredturn in azimuth at any point in its flight."

"30. In combination, a self-stabilizing,self-steering aircraft, means comprising aradiant energy transmission system forcausing said aircraft to make any desiredturn in azimuth at any point in its flight,and means for automatically banking thecraft while turning."

As a result of the Hammond-Sperryagreement of 1925, all later radiant energyairborne-guided missile-type equipment pro-duced by Sperry involving a change of astabilized course, carried Hammond patentnumbers. Pre-World War II radio-guidedaeroplanes came to be known as Ham-mond-Sperry Drones.

Additionally, it is to be noted that auto-matic pilot systems commercially developedfor passenger planes with a pilot in attend-ance are covered by the basic patents ofHammond filed in 1913, such as that citedin the discussion of Section 11-9 above.

Therefore we submit that Hammond,and not Sperry, was the true pioneer in thedevelopment of the "automatic pilot" forwaterborne craft, and that patentwise, theinvention is dominated by patents that wentexclusively to the U. S. Government in1932; that Hammond's gyro-pilot ideas ap-plied in the waterborne field were also ap-plicable in the airborne field, regardless ofwhether there was a human pilot also avail-able, or whether the craft was radio-con-trolled; that in the explicit field of radiantenergy control of airborne torpedoes inwhich he was not obligated to the Govern-ment, Hammond granted the Sperry Com-pany exclusive rights which it acknowledgedand exercised in pre-World War II aerialtorpedoes and the like. Hammond pioneeredthe "automatic pilot" and both Hammondanid Sperry produced it. Sperry24 did nothesitate to regard Hammond as a personalfriend as well as an associate in this de-velopment.

13) Critique. "But ahead of Tesla, ap-parently, were the two British inventors,Wilson and Evans.... The receiving con-trol electromagnet is made dependent for itsoperation upon the receipt of both chan-nels..

Rebuttal. The cited patent in Fig. 7shows such a control magnet. However,there does not seem to be any patent claimspecific to this manner of practicing the in-vention, nor to any security advantages.The Wilson and Evans arrangement wouldbe suLbject to interference on a "channel"intermediate between the horizontal andvertical polarization "channels": the Teslasystemii would not so readily be forced byany single channel, since in the Tesla sys-tem, the word "channel" is in the usualfrequency sense. It is the Tesla system that

24 Letter of Sperry to G. A. E. Lundeii, October

21, 1926.

is the background of the Hammond single-shot FM system of security used on theNatalia.

14) Critique. "de Forest had devised...a diplex system of telegraphy.... "

Rebuttal. Such a system is irrelevant tothe discussion. Hammond's system wassimplex, depending upon the reception ofboth ends of the transmitted spectrum toestablish a single control signal. The deForest system, apparently, was diplex, withone end of the spectrum for conveying onemessage and the other end for anotherindependent message. There was no co-operative action between two channels toproduce a single signal as in the Hammondsecurity system and as in modern FM re-ception.

15) Critique. " . . . the claim is for atorpedo, meaning in water.... "

Rebuttal. The words "as set forth" do notappear in the claim, therefore the claim isnot limited by the drawings and specifica-tlons, but only by the allowable breadth ofthe words "torpedo" and "energy." We con-sider the word "torpedo" applies to aerialtorpedoes, and that "energy" applies toelectromagnetic energy. Note that contraryto the statement of our critic, the word"fuse" is absent from our paper. While the"proximity fuse" principle may apply toairborne devices, the "proximity" principleapplies to both air- and waterborne devices.Neither we nor presumably our critic are ina position to know whether or not the prox-imity principle, in fact, has been applied inboth media.

III. THE TRIODE TUBE

16) Critique. "The quotation is correct,but the assumption that it referred to thetriode rather than the diode, as of 1906, isin error."

Rebuttal. On the contrary, our assump-tion that it applied to the triode both in1906 and also later is not in error. TheMarriott reference in its entirety on thispoint is:

"5. Audion. This form of detector wasused to some extent as early as 1906, butapparently in small numbers until about1912 when the amateurs became active inits use, and within the last year or more ithas been used to some extent by the Gov-ernment. "

Now our critic later states, "It was aboutthat time that the grid audion began to comeinto some use, 'but apparently in very smallnumbers' as Marriott said." Since Marriottreferred to "this form of detector, " andsince the form of detector as of 1907 was thegrid audion form, as our critic admits, itfollows that Marriott was referring to thedetector of 1906 as a triode. Our critic doesnot openly say that the Marriott statementwas in error, but does say that we were inerror in interpreting it. Our critic, in hisfirst printed discussion of the Marriott paperin the PROCEEDINGS,25 failed to challenigethe Marriott statement in this matter, ashe muist now do.

17) Critique. "The grid triode appears tohave been invented toward the end of thatyear or the beginning of 1907."

25 L. Espenschied. 'Discussion.' PRoc. IRE. vol.

5, p. 196; June, t917.

Rebuttal. The patent application coveringthe invention of the grid triode26 was signedby de Forest on December 21, 1906. There-fore, since de Forest undoubtedly used thegrid triode in 1906, it appears that theMarriott statement as to dates is just ascorrect as our interpretation of it.

18) Critique. "It .. issued as a patentFebruary 18, 1907.. . . (There was no timelost in those days!)"

Rebuttal. The grid triode patent referredto issue February 18, 1908. The parentheti-cal statement shows that the error could nothave been due to any typographical error ofthe printer.

19) Critique. "Amoing those small users,to the writer's knowledge, were a fewamateurs.... The writer, with two otheramateurs ... attended de Forest's Brooklynlecture..

Comment. Our critic, according to"Who's Who in Engineering," joined theengineering staff of the Telephone Companyin 1910. There was, therefore, at least onemember of the Telephone group who knewof the de Forest triode two years before theTelephone Company, as our critic laterstates, learned about it in 1912.

20) Critique. "The grid audion detectorcontinued for some years solely as a detec-tor."

Comment. The critic here lapses into theearly usage of "Audion detector" as meaninga triode tube regardless of the use to whichit was put in circuitry.

21) Critique. "But they do not tell thewhole story and give the inmpression ofHammond's role having been more thani itwas. "

Rebuttal. There was no need of tellingthe whole story. The prior attempts at de-veloping the triode were recorded in the firstand last parts of the paragraph, showingthat Lowenstein still, in 1912, had a lot moreto develop. Hammond's immediate interestwas the procurement of a better type of"relay-operating rectifier-detector," and inthis branch of the work, Lowenstein nmayhave been a true consultant. At least, henever changed the words "ConsultingEngineer" on his letterhead27 when writingabout any phase of the ion controllerproject. Hammond's role qtuickly becamethat of an unsecured creditor, buLt withpaper rights in exploiting the triodedevelopments. On the basis of personalfriendship, a settlement of financial matterswas made with Lowenstein about threemonths before his sale of the grid biaspatent to the Telephone Company, at sucha figure that the entire amount receivedfrom the sale went directly to Lowensteinas a clear profit. The Hammond role was notexaggerated in the paper.

22) Critique. "The term 'controller' or'ion controller' was Fritz's alias for the natne'Audion' which de Forest had bestowedupoIn Fleming's tube upon adding to it the'B' battery."

Rebuittal. This is greatly in error. TheLowensteini "ion controller" was a triode,and not a Fleming diode. Our critic mayhave confusedly substituted a battery ex-

26 U. S. Patent 879,532 to L. de Forest.2 Letter of Lowenstein to Hammond, November

13, 1911.

1959 1263


ternal to the Fleming valve, where he mnayhave meant a grid within the valve.

23) Critique. "The strange thing is thatit was not followed up."

Rebuttal. Our conijectures as to why thework was dropped by Lowenistein are statedin the paper. Lowensteini's research wasmade available to the General Electric Com-pany,28 with nmore facilites and comiipetenicethan Hamimond-Lowexestein for carryingout "a systematic inivestigation of the in-fluence of the vacuLum." Dr. G. \W. Pierceonce recalled to Us, "We were not at all surethere was any great fututre for the triodetube, but felt that any fuitture lay in thedevelopment of the hard tuibe." The hardtube was a General Electric dlevelopllleInt.

24) Critique. "And it is sinigtilar that toHammond, 'The exact natture of the ionicdevices and the manner of operationi are notknown'."

Comment. The technical details may bein the Lowenstein files concerninig which ourinquiries have been futile. There is a sug-gestion of a method of regenerationi in thebook, critic's reference 27, in the figure of adetector circuit for which u-nusual senisi-tivity was claimed. (See Fig. 77, p. 133.)

25) Critique. "One wonders . that theevidence of . . an oscillation generator .

was not presented to the courts."Rebuttal. There is a statement of the

oscillatory use of triodes in the book, critic'sreference 27. (See p. 179.)

26) Critique. " . the letter whichHanmmonid wrote the President of thatcompany.... "

Comment. This action proves, if nothingmore, the Hammond objective of gettingradio-electronics on a foundation free fromforeign domination. It also discredits thecritic's view that all of Hammond's work wasconducted in secret.

27) Critique. " . . a copy of the letterswas sent to him.....

Comment. We wish to make it clear thatthe letters were not given to ouir critic forthat purpose.

28) Critique. "Arnold later testified ...'I was very ntuch astonished and somew hatchagrined....

Comment. Arnold's chagrin must havebeen matched later by that of our critic whohad known of the superiority of the deForest detector during two years of engineer-ing service with the Telephone Companiy.

29) Critique. "There was ordered fromGermany the latest type of vacuum pump."

Comment. Trhis is a point of importanthistorical significance, since it shows theTelephone Company work was mnuch laterthan that of the General Electric Companyin the prodtuctioni of high vacuum tuibes.

30) Critique. " . . the company origi-nally could have had the patenit for $20,000. "

Comment. The Lowenstein patent wasutsed by the Telephone Company in mianyinfringemllent suiits, and presulmably made aprofit eveni at the final figture.

31) Critique. "Actually, Lowensteini andHammllond, by coniing inlto the picttire whenthey did ... performed a major service.'"

Comment. Mr. Hammond, by foreigntravel and contacts, realized that the growth

of the "Telefuunken'" and other foreign com-panies, and their penetration into the UnitedStates, could be checked only by interestinglarge electrical companiies in getting intothe communication and equipment field.Appearing before the board of the GeneralElectric Company for the purpose of in-teresting it in an American radio company,he was unable to make the progress laterachieved by the efforts of the Navy Depart-menit. It is gratifying to learni that his in-direct approach to the General ElectricCompaniy, the Telephone Company, andthe Federal Company is getting to be ac-cepted as a major service.

32) Critique. "It must have beeni inearly Novemiiber, 1912, that de Forest wasin Gloucester. "

Rebuttal. The premise that de Forestfirst went to the Bell people is in error. Ourdocumentation is a letter29 and a telegram30which places de Forest in Gloucester in lateOctober, as stated in the paper. The visitwas not in connection with the amplifierwork of either de Forest or Lowenstein, andthe information was casually given.

33) Critique. "As if it were niew, Ham-ii.ond referred it to the General ElectricCompany as 'the proper triode design'."

Rebuttal. TFhe clause "as if it were new"is unijuistified. It was an engineering design,expressing the personal views of the mem-bers of the Hammond group. This designwas not at first followed by the GeneralElectric Company for the reasons stated.Nor was it followed by the Telephone Com-pany in their first wartime type E and Jtubes. The original pencil sketches, of whichouir critic presumably has a copy,3" carry twodated signatures. These are the signaturesof attorneys of the General Electric Com-pany, and not of anyone of the Hammondgroup. In fact, the only direct indication ofthe Hammond source of the design is thatthe material would be recognized as beingin the handwriting of Dr. G. WV. Pierce, thena consultant to the Hammond Laboratory.Not even he bothered to sign the sketch.

IV. MODERN INTERMEDIATEFREQUENCY CIRCUITRY

34) Critique. "In a patent interference,Hammond was awarded a claim which heinterprets as giving him 'the broad subjectmatter of intermediate frequency cir-cuitry'."

Rebuttal. Our statement rather was, "thebroad subject matter in controversy wasawarded Hammond." WVe have very clearlystated oir belief that Hammond contributedthe selective features of intermediate fre-qtuency circuitry, while it was Alexandersonwho, due to his development of the TRFamplificationi idea, contributed the sensi-tivity features. The withdrawal of the Levypatent application from the interferenceshould not be overlooked.

35? Critique. "In 1909-1911, the Tele-ftinikelln. . ..

Rebuttal. The Telefunken equipment wasnot pertinent to the decision in the inter-ference, because what our critic calls a

second detector was not a detector. In fact,our critic later states parenthetically: "Thetone-frequency signals, instead of beingrectified, could be read in headphones or ona loudspeaker." Apparently, our critic'ssubconscious mind compelled him to uise thecorrect word "rectified" as applied to a to0nalfrequency signal. and it was only his coni-scious mind that has attempte(d to call thatrectifier also a detector. As ouir critic andformer advisor of attornievs of the T ele-phone Company well knows, suibconisciouslyat least, the question of wheni a rectifier isalso a detector was thoroughly discussed inthe interference. Our critic gives no patentnumiber for the Telefunken equipmienit. Itsoperation in the respect here discussed isunquestionably subservienit patentwise toearlier references cited by the TrelephoneCompany in the interference. A brief reviewof that case appears to be in order.

Elhe patent claim that has been ctitedoriginated with Heising or his attorneys. ItsooIn developed that, if patentable, Hanm-mnond would win the claim over Heising andover Levy. Levy withdrew. Thereuponi, inaccordance with usual legal procedures, theTelephone Company, in order to try for apartial victory, attempted to prove its ownwritten claim was actually unpatentableover art prior to both Heising and Ham-mond. Cited, for example32 were Fessenden727,326; Fessenden 752,894; Blondel 824,682;and Scheller (German) 208,836. TFhe Schellerpatent was cited especially to upset theclaim as to "selecting a componient" and theothers more especially to upset the claimn asto "detecting said selected component."These efforts of the Telephone Companywere unsuccessful, and would also have beenunisuccessful if the well-known Telefunlkenequipment had also been cited. If there wasanything established technically by theinterference, it was that the word "detector,"relates to a device involv ed in the finding ofsomething hidden, and therefore a deviceacting upon audio-frequency currenlts al-ready being indicated by headphones or aloudspeaker cannot be termied a detector.If therefore follows that the circuit precedinga second detector must containi currenits ofa frequency or frequencies above the audiblefrequency range. Our concept of intermiiedi-ate-frequency circuits was clearly stated atthe beginning of the section, and it is in ac-cordance vith presenit accepted usage.

36) Critique. " the Patent Officemust have overlooked prior art."

Rebuttal. The Patent Office considleredcarefully, at the very top level, all the artwhich the experts of the Telephone Corn-paniy presented. If the Teleflunken equiip-menit had been pertiinenit, alnd it was not,aniy failuire to uncover it wotuld not be charge-able to the Patent Office, since this was animportant interference and not a Lusualsearch case involving Patent Office personlnelonly. The final legal decision was by threeExaminiers-in-Chief, paper 67, January 27,1922. Because of the importance of thematter, the papers then went before WilliamA. Kirman, First Assistant Commissionier,so that both parties would have the informalviews of even a higher official of the Patent

28 Letter of Alexanidersoli to Hammond, October21, 1912.

29 Hammond to Lowenstein, October 24, 1912.30 Hammond to Lowenstein, October 23, 1912.31 Enclosures in letter of W. G. Gartner of the

General Electric Company to Hammond, July 1, 1913.32 Brief for Heising, U. S. Patent Office Interferenice

43,858, Paper No. 64; October 21, 1912.

1264 July

Discussioni of "A History of Some Foundations of Modern Radio-Electronic Technology"

Office. On January 29, 1923, he wrote:"There is no appeal frotn this holding of theExaminers-in-Chief that Count 4 is patent-able. . . This patent to Scheller does not,in my judgement, disclose any 'means forselecting a component of said selectedenergy'.... The decision of the Examiners-in-Chief is affirmed." And on April 13, 1923,Mr. Kirman further wrote: "As to the allow-ance of the claim to the party Hammond, itmay be allowed in any application in whichit can be properly made. " The case isfinished, the Telephone Company boughtrights under the Hammond patents, thepatent numbers were put Uponi equipments,the patents have expired. It is rather latefor a consultant of the Telephone Companyto now suggest that the Patent Office over-looked such a well-known "Telefunken" artand that the Telephone Company boughtpatents that were invalid.

37) Critique. "Hammond cannot becredited with originating the double-detec-tion technique, starting, as it did, withauidio-frequency IF."

Rebuttal. Readers will be amazed to findsomeone who as of the present date will referto an audio-frequency intermediate frequency.

38) Critique. "Of Alexanderson's 1912tuned-radio-frequency circuit shown in Fig.12....

Rebuttal. The caption of this figure doesnot justify this interpretation. The circuitshowni originated with Alexanderson afterhis invention of TRF in Gloucester, andcanie to Hammond in a letter of October 21,1912.33 The word "later" in our paper shouldnot be overlooked. For the purpose ofshowing the relations between the TRFsystem of Alexanderson and the IF systemof Hammond, we were entitled to hypoth-esize the devices commonly termed "Audiondetectors" or simply "detectors," either asactual detectors or as actual amplifiers.

39) Critique. "One reads: 'Fig. 82 illus-trates a type of transmitter-receiver unitsuggested by the writer in 1911."

Rebuttal. The implication of this state-ment is most readily refuted. Fig. 82 of thebook cited corresponds almost exactly withtwo figures of U. S. Patent 1,491,773. ThatHammond was the inventor of the patentedmnaterial shown in this patent is evidencedby his signature at the end of the specifica-tions. If our critic does not consider thissufficient, the fact that Miessner was not theinventor of the patented material is evi-denced by his signature as a witness. Ourcritic presumably has failed to note an al-leged relation between the receiver systemof the figure cited and the TRF circuitry ofAlexanderson, available in a reference34cited in our previous paper.

40) Critique. "Another claim for a 'first'muLst be corrected."

Rebuttal. In preparing our paper, weendeavored to leave out any reference to theword "Hammond" wherever we consideredthat there would be no misinterpretation asto the meaning. Most readers, we believe,made a mental insertion of the words byHammond after "was first applied" in thecited passage.

33 Alexanderson to Hammond, October 21, 1912.3' Authors' previous paper, footniote 32, p. 1198;

see p. 1366 of the reference.

41) Critique. "The apparatus is said tohave been.... "

Rebuttal. Some may construe this methodof expression to convey doubts on the partof the critic that the alleged equipment everexisted, or, if it existed, that it ever went toFrance. Our records show that on Novem-ber 2, 1918, a conference was held at theDepartment of Development and Inspec-tion,35 Signal Corps, A.E.F., in France, todiscuss this Hammond equipment withMessrs. Chaffee and Buswell of the Ham-mond Staff. Present were General Russel,Colonel Carty, Captain Armstrong, andLieutenant Fahys. From published bio-graphical material, it is most certain thatColonel Carty ("who during the wholeinterview was polite and cordial") was thenalso the chief engineer of the TelephonieCompany, and one with whom Hammondhad had dealings in 1912 in the Lowensteinamplifier matter. Our critic undoubtedlycan check with the records of the TelephoneCompany to settle his doubts in this matter.

42) Critique. " . . the short wave multi-plex radio telephone system developed bythe Western Electric Company.... "

Comment. This is presumably the equip-ment uipon which the party Heising prop-erly wrote the patent claim which has beencited. If so, this equipment was later provento be subservient to the prior Hammond art.The time lag between installation and pub-lication is noted, but without surprise. Coni-temporary equipment upon which pub-lication was also delayed included theHammond IF system that had been pre-viously used in control work, and that uponwhich construction was started in 1917 andwhich was delivered in Europe in 1918. Thecomparison between the merits of theHeising naval equipment and the Ham-mond military equipment is out of order.The Telephone Company work was incommunication between ships; the Ham-mond work was in finding a military solutionto such problems as avoiding the necessityof requiring U. S. Infantry to advance intoits own Artillery barrage.

43) Critique. "Of course both detectorswere 'of an oscillatory nature,' detection ofoscillations being their function."

Rebuttal. This statement is improperlybased upon a confused concept of an oscilla-tory detector. Crystal diode detectors weredetectors of oscillations but they were nottherefore oscillatory detectors. Althoughthe first detector of the equipment underdiscussion was advisely used in the non-oscillatory condition for the proper recep-tion from the corresponding military trans-mitter, it did often oscillate during thecourse of making adjustments. Under theseconditions, the circuit most certainly had thestructure of a CW "superheterodyne" re-gardless of whether or not there was anyCW to be received. We fail to understandwhy our critic is disturbed by our remarkupon this point, since the CW "super-heterodyne" is an Alexanderson inventionin whatever respects it is not a Hammondinvention, as now to be recorded.

44) Critique. "The first to arrive at thetrue superheterodyne and apply for a patent

3a Compare this address with that of p. 5 of thereference in the authors' previous paper, footnote 62.

upon it, was one Lucian Levy of Paris."Rebuttal. This is in error. The French

patenit to Levy was filed AuLgust 4, 1917,and his U. S. Patenit 1,734,038 was filedAugust 12, 1918, with an additional figure.This U. S. patent later received claims1, 2, 3, 6, 7, 8, and 9 from the well-knownArmstrong patent. These claims relate tothe amplificationi of readily amplifiableintermediate frequencies in the telephonic-type sLuperheterodyne. At the same time,and in the same manner, Armstrong claims4 and 5 went to Alexanderson U. S. Patent1,508,151, and claim 4 remained there asclaim 20. This relates to the amnplification ofreadily amplifiable intermediate frequenciesin the CW-type superheterodyne. This U. S.patent was a divisional patent based upondisclosures that are also in a prior Alexan-derson patent 1,465,961, filed April 19, 1916,over a year before the date of Levy's filingin France. This is the effective filing date ofboth the Alexanderson patents, and ittakes precedence over Levy as to the gen-eral concept of amplifying a readily ampli-fiable IF in a superheterodyne. Beforeboth Alexanderson and Levy, Hammond in1912 had filed upon his U. S. 1,491,774which specifically covers the telephonic-typesuperheterodyne structure, but of coursewithout the addition of tuned amplificationof superaudible frequencies which was alater Alexanderson contribution, also of 1912.

45) Critique. "Hammond's works wereentirely unknown in France in 1917."

Rebuttal. This statement is in error.Hammond at that time had several patentspending in the French Patent Office. Radio-dynamic patents 474,906 and 475,888 hadbeen published in 1915; intermediate-fre-quency patent 519,811 was entered into theFrench Office on December 12, 1917, basedupon U. S. Patent 1,491,775, filed September28, 1916.

46) Critique. "Thus it is apparent thatIF technology came into being and wentinto service quite independently of Ham-mond's more secret efforts in the field."

Rebuttal. This statement is not justifiableby the facts. That Hammond's efforts werenot secret even from the pioneer in thecornmercialization of the superheterodyne,and that they had a very definite techno-logical bearing is evident from the followingincident. On November 8, 1918, CaptainE. H. Armstrong requested the presence ofDr. E. L. Chaffee to explain a technical pointas to the proper design of intermediate-frequency transformers. The desired infor-mation was freely given.

V. FREQUENCY MODULATION ANDRELATED SYSTEMS

47) Critique. "A Hammond patent iscited...."

Rebuttal. Our critic apparently cannotthink back to the period of the filing date ofthis patent, when receivers were very broad-band, CW signal rates were twenty wordsper minute, and key shifts were 300 cycles.The patent certainly could be practicedwithout serious cross-signalling, just as canits modern television counterpart. There areother patents in the Hammond group, andother pertinent Hammond activities, thatmake the tie between the early patent and

1959 1265


modern color TFV technique more close thanwould appear from our paper.

48) Critique. "The presentation of theChaffee transmitter of Fig. 16 as a part of a'noise reduction systemn' is misleading. . "

Rebuttal. The systemii u1ndertook to re-dtlice all noises coming inlto the receiver- in-sofar as they prodLuced equal effects incirctlits tuned to the two ends of the spec-trtmn. Hutm reductioni was cited as an ob-viouls example. The system also reducesdisturbances that are not so equally presentin both ends of the spectrulmi. Our criticshouild check the nature of the spectrtumshown with that of a sinie-wave FM signialwith a modulation index of 2.4 to see thatthe Chaffee system had the noise reductionmlerits of moderni FI\l svstems, except as toamplitude limiting.

49) Critique. "Appearing iniitially as afault, the making of a virtue of this effectwas a natural second thought."

Rebuttal. Knowledge of this effect evenin the early broadcast branid of frequencieswas the basis of the 1921 vork of our juniorauithor in developing the lirst all-electronictype of FAiM translmiitter-, with perform-;lanceas indicated in Fig. 15.

50) Critique. "Chaffee of the Bell 'rele-phone Laboratories thus sought to utilize itand devised a receiver for an FM system."

Comment. By the critic's footnote refer-ence to the papers of J. G. Chaffee, thiswork was published in 1935. By that time,nearly all the really basic wAork in the fieldof FM had been comiipletecl and the im-portant patenits of the workers cited inl ourpaper ha(l come to issue. It is further be-liex ed that the Telephone Comiipaniy wasamonig those which had rights unider thepatents and the patent applicationis coverinigthe Hammond Laboratory work ini thisfield. If it had so desired, the TelephonieComlpany could have made a good comiiiiier-cial beginniing in the FiI field on the basisof the Hamiimond patents alone.

GENERAL COMMENTSOur critic's attempts to downgrade the

judgments of contemporary experts as tothe value of Hammond's work are not thefirst. At least three prominent pioneers inradio-electronics advised the Governmentagainst taking its initial step in radio guid-ance of missiles. The acting Secretary ofWar,4 in rebuttal advised Congress, ineffect, that: Hammond's work was far ad-vanced over the prior art, with a hundredpatent applications and a thousand allowedclaims; the patenits of Rear Admiral Fiskewhich some claimed to be basic would expirein about sixteeni moniths, so that there waslittle danger of trouble from the WesternElectric owners; Hammiiiiond was holding theGovernment free from liability in case of in-frinigement suits; an(i the actual risk wasbut $30,000 since the Government wouldnot be obligated incase of an adverse reportby the newly-to-be-created Board. Therecommendations of the previous Army andNavy officers had been so favorable thatCongress had no hesitation in proceeding.The value of the inventions, developmentsand patents had been affirmed by the legaldepartments of the Army and the Navy,and is most genierally accepted by officersand others who have examined the facts. As

to the field of initermediate-frequency cir-cuitry, chief patent attorney George E. Folkof the Telephonie Company coniferred withHammond ev,en before the terminationi ofthe Heising initerferenice, and acknowledgedthat Hammilonid was goinig to be the winniier.Therefore he took steps to secture riglhts tin-der the Hammlloind invenitionis anid patentsfor the Telephonie Companiy and furtheradvised the Radio Corporation he thoughtit shouild do likewise. rhis action, couipledwith the direct findings of the Radio Corpo-ration anid similar advices from others in-clhdinig E. H. Armstroiig, resuilted iii theHammiiond work becomiiing immllediatelyavailable to the iniduistry withotit anyfurther litigationi.

CONCLUSIONIn concluisioni, wve deeply regret the

necessity of having had to point ouit themany errors of simple facts on the part of ourcritic. We regret the necessity of havinig hadto correct so many misinterpretatioins of ourstatements in the paper, on points thatshould not have distuirbed himn and others.\Ve regret the niecessity of having had to goinito more personial matters, to show how thevarious developments appeared to others atthe times at which they were being miia(de.By failing to commnient uponi other mattersthan the fifty items here discussed, we do notwish to be considered negligent, if there areerrors of fact inl the extraneous materialpresented in the critique.

JOHN HAYS HAMMOND, JR.E. S. PURINGTON

Hammonld Research Corp.Gloucester, Mass.

Replication of Rebuttal byMr. Espenschied*

Of the fifty points of rebuttal, only a fewneed further attention:

3) Of the twin Fiske patents of 1900 onthe wireless control of torpedoes, Nos.660,155 and 660,156, Hammond in 1912called one of them "the first" of its kind,when seeking inifornmation about it, as al-ready noted. Subsequenitly he ignoredFiske, and now the authors reject him. Inclaiming Haninmond did niot infringe Fiske,there is quote(d a claim, obviously broad,with the coontentioni that the words withwhich it ends, "as set forth," limit its scopein some unspecifiedl manner. This refusal torecognize a predecessor lends significance tocertain additional information knowni to thewriter which is now presented in jtistice toAdmiral Fiske.

When in 1915-1916 Hammond was sell-ing to a war-worried Uncle Sam his ownproject of a wireless-controlled torpedo-which never succeeded-Admiral Fiske be-came concerned lest his patents be infringedand wrote the company to which he hadassigned them, the Western Electric Com-

* Received by the IJRE, November 3, 1958.

pany. TI:hat company then had the mlatterstudied by a college-professor patenit at-torney, P. 1. Wold. On March 9, 1916, hereported to Western's Patent Counsel, l). C.Tanniier, saying "we haxe miiade a study ofthe Fiske Patenits and certain patenits toHammlloind, who is a possible inifrinigingpartx." He conlcluded:... that the claims of the Fiske patenits are valid, arenot subsidiary to other patents and are basic in scope.His arrangement is operative. Hammond has a patentfor a somewhat similar device but his claims arelimited to his specific apparatus and are furthermloresuibsidiary to the Fiske claims. We are also uinlable tosee, at present, how Hammond or others can make aliydevices of this nature without infringing Fiske'spatents. Fiske's patents, however, expire in about 19months and any steps, such as inifringement warnings,shouild therefore be taken in the near future. In vieswof Court decisions on Government contracts it maybe that Hammond or others will igniore these patenits,in which case our only recourse will be to the Court ofClaims.

On March 10, 1916, Tanner sent to hissuperior, Mr. Swope, a copy of the Wold re-port. He recommended against taking "anysuch actioni against the Government,...in view of otir relations." He suggested thecomlpany offer to ttirn back to AdmiralFiske his two patents, "tipon repaymenit byhim of what they have cost uis." 'rhey arenot kniown to have beeii repossessed byFiske. Probably he realized only too well thetrials an(d expenise of a lenigthy law suit. Heis not knownl to have gaine(d aniything fromhis iinaginative and patriotic ed(leavor; anidnow we see him denied eveni recogniition.Stich is hardly objective technical history!

6) Three statemenits in the originalpaper gave the impression that Hanmiiiionidclaimiied to have developed, in 1910-1914,the printciples of atitomatic cotirse stabiliza-tioii by mieanls of the gyro:

Many developmenits by the hlammonld Labora-tory established basic priniciples used in moderni air-borne guiided missiles, including the stabilizationi prini-ciple.... (Stummary of paper.)

Preliminiary work by tliammonid resulted inthe development of the atitomatic course stabilizationprinciple (p. 1192, coltumniii 1, lines 27-30).

Automatic Course Stabilization.... The firstnavigational application of tluis automatic pilot prin-ciple was to the third boat, the Natalia of Fig. 2;the system was first put into lonig period operationon March 25, 1914.... (P. 1192, columni 2, linles34-38.)

Surely these claims give that impressioll.But all is well, Inow that the auithors deiiysuch intention.

12) The insistence of the authors thatHammond, and not Sperry, was the trtLiepioneer in the developnment of the "'auto-matic pilot,' goes qtiite against the writer'simpression, and dotibtless of many others,but he will not ftirther press the poinlt,leaving it to others better qualified to jtic(ge.Perhaps the Sperry people will have somiie-thing to say. Here is a good examiiple of themaniy versions onie canl lhax-e of a certlaintechniological origini, dlepend(illg Lipon] theviewpoint.

15) Hammonid U. S. Patenit 2,060,198describes a torpedo in water and electro-mechanical mieains for com inn-nicating bycompression waves with the object to bedetected. In the absence of the disclosure ofanother meditin and corresponding com-munication means, the term torpedo in theclaims is to be constrtied in its ordinarymeaning of a waterborne body. Hence, theattempt at making the claimi read on theradio-controlled proximlity ftise by callingthe action the "Proximity" principle, ismisleading.

1266 J11/Zy

Discutssion of "A History of Some Foundations of Modern Radio-Electronic Technology"

16), 17), and 18) Robert Marriott'sstatement concerning the early use of theAudion, namely that:

This form of detector was used to some extent asearly as 1906.

is quite correct if it is understood what "thisform of detector" was as of 1906. It was thediode, or two-element form, with "B" bat-tery added by de Forest, as described in his1906 AIEE paper entitled "The Audion."Marriott was well aware of this, the first,form of AtLidion, and was not limiting him-self to the suibsequient form, the grid triode,wlhich later "stole the show." It was theauLthors, Hammon-d and Puringtoni, who solimiited him, by inserting, in c(onnectionwith his statement, the words "three-elec-trode form of detector." Therebv Mar-riott's statement was altered, mlakinig thetise of the grid Auidioni appear somewhatearlier than was the case. A small poinit, buttone worth keepinig straight historically.

The grid Audion was invented in thewinter of 1906-1907. It began to be "uisedto some extent" not until 1907 to thewriter's knowledge. The first puLblic dis-closuire of it was by de Forest himself in hisBrooklyn lectuLre on "Wireless" of March 14,1907, already mentioned. The patent for thegrid Auldion was applied for Jantuary 29,1907. It isstied February 18, 1908 (not 1907as previously stated by the presenit writer,an error he is glad to have corrected)-No. 879,532.

22) The authors appear not to haveuntiderstood the comment. Fritz Lowenstein,employing de Forest's grid Audioni, butwishing another name for his own purposes,called it an "ion controller"-much as hadde Forest re-christened the Fleming Valve,to which he added a plate voltage, callingit "The Audion" as per his 1906 AIEE paper.How interleaving are inventions, buit howreticent inventors to admit it!

29) The present writer mentioned sev-eral steps taken by Dr. H. D. Arnold in thetelephone companiy's laboratory in attain-inig higher vacuum and generally improvingde Forest's grid Audion, one of them beingthe importinig of the latest kind of vacuumpuLmp, the Gaede molecular, received inApril, 1913. From this date, the authorsassert " . . . the TIelephone Company workwas much later than that of the GeneralElectric Company in the prodtuction of high--acuum tubes." Quite the opposite was theconclusion of the SuLpreme Court of theUniited States in the famous Arnold-Lang-mnuir litigation over the high-vacuLutm tube,where the telephone company's priority wasrecognized in these words:Augutst 20, 1912, the earliest date claimed for Lang-muir was rejected rightly, we think, by the districtcourt, which held that Langmuir was anticipated byArnold in November, 1912.1

The high-vacuum tube, in its use in trans-mitting as well as receiving, over wires aswell as by radio, proved to be second onlyto the grid Audion itself as a cornerstonie ofmodern radio-electronics.

I The decision, handed down May 25, 1931, recog-nized also that de Forest himself had gone part wayto high-vacuum, without fully knowing wvhat he wasdoing. Published in "Cases Argued and Decided inthe Supreme Court of the United States," Book 75,Lawyers Edition, 1931. De Forest Radio Co.. Peti-tioner, vs General Electric Co., No. 660.

Finally, a personal note. The writer'sdiscussion of the Hammond-Puringtonpaper has been offered to balance its ex-cessive claims, in the interest of more cor-rect technical history. The writer is not aspokesman for the telephone company, hasnot consulted the company, from which hehas been retired some years. He has merelyused knowledge that came to him in a longactive career in the field.

Comments on "Replication ofRebuttal" by Mr. Hammondand Mr. Purington*

At the outset, we wish to thank our criticfor making clear to all what we had longsince sensed, that his "Critique" of our Sep-tember, 1957 paper in the PROC. IRE wasnot reviewed by an executive of the Tele-phone Company. We are pleased that wemust proceed further with only nine of thefifty items which we disctissed in our firstresponse. Our final comments follow.

3) The Fiske Patents: In otir files, theonly statement by Admiral Fiske concernin-gthese patents is that made in the high-policyconference of February 9, 1916, (our rebut-tal reference 9a, p. 35 of the report): "RearAdmiral Fiske: I stIppose yotu understandthat I am not an unbiased witness. I wantthat uinderstood. I invenited this generalscheme in 1897 and got a patent on it, andthe patent has not expired. It is a basicpatent. I want that tunderstood." There wasno mention of any reduiction to practiceeither by Fiske or by the Westerni ElectricComupaniy. Otr interpretationi of the word"tas' in the phrase "as set forth" is the dic-tionary meaniing "in the samne manner." 'Wefeel no patent lawyer would accept a claimwith the words "as set forth" at the end ofan otherwise basic claim unless by comptil-sionl. We did not quote the Fiske claim, buta very similar Tesla clainm. By the words

... our only recourse " in the Woldreport to Tatnner, it would appear that Prof.P. 1. Wold was more closely related to theWestern Electric Company than our criticwouLld like his readers to believe. Upon con-tinued study of the patents after his inquiryconcerning them cited by our critic, Ham-mond found design errors which experts be-lieved rendered the struictures inoperative.Even after the Tanner recommendationi notto take action against the Government, thepossibility of such action was called to theattention of the Government by another andpresumably disinterested engineer, to whichHammond responded by guaranteeing tohold the Government harmless in case of anyand all patent difficulties. In a paper cover-ing contributions to technology, it wouldhave been improper to refer to one as apioneer whose inventive effort was not re-duced to practice by himself or by others ashis agents. Please note, however, that inrebutting our critic in this matter, we do not

* Received by the IRE, May 13, 1959.

wish to create the impressioni that we do nothave great admiration for the extensivepioneering work of Fiske in other fields ofnaval development.

which never succeeded . . . " is acomplete misstatement of fact. The Ham-mond torpedo-control system tested by theNavy at the Newport Torpedo Station ful-filled the exacting requiremetnts of the Chiefof Naval Ordnance, and the report of thesesticcessful demonstrationis was giveni bx Ad-miral Leahy to the Secretary of the Navy.The non-tise of the device was tltie to navalpolicy and this was formulated upon theproblem of mass produictioni for war aniddiffiCulties encounitered with the new mag-netic detonators. lThe Hammilond(I conitrolsysteim was widely used in the control ofnaval targets, anid the Hammiiiiond-Sperryinventions created the target "drones" andfinally the basic control of moderni missiles.

6) Developments of 191-1 914: The seti-tences which gave our critic trouLble will, webelieve, not confuse those who take theadjacent sentences and paragraph headingsinto considerationi.

12) The Automatic Pilot: Others betterqualified to jutdge will first conisider themeaninig of the word combination "atito-matic pilot. " Theni we are tonfident thatthey will not have diffict-lty in differentiat-ing between the contribtutionis of Sperry anidof Hammond to the navigational art.

15) The Proximity Principle: Patentsare written to be read anid understood byexperts. The terms used are to be interpretedas broadly as expert tisage will permnit. Asregards this patent, the expert uisage hadbeeni established for more than a decade.Thus, during the conference of a distiti-guished group of high officers with Hamn-mond at Fort Monroe, Auigust 23, 1918, thefollowing was officially recorded. (Emphasisis by tLis.)

"General Sqtuier: Yotu have showni thisafternioon the conitrol of the regular torpedoin water both by the radio device and also byacoustics. Why do you limit yotlrself towater? Why don't you get an aerial torpedo?

"Mr. Hammond: I have covered that eni-tirely from the standpoint of patents. rhereason that I have not given it more thouLghtis that I amii specifically attacking the tinder-water section of capital ships.... I havenot made any experimenits; I have merelyconcentrated on this proposition for theCoast Artillery.

"General Sqtiier: Is the aerial torpedo aharder problem?

"Mr. Hammond: It ishardertomy miind."Note that in a single paragraph, the

Chief Signal Officer of World War I referredto two kinds of torpedoes and to two kindsof energy by which they may be controlled.Clearly the examiner of the proximity patentyears later would have reqtiired Hammondto insert underwater before "torpedo" andacoustic before "energy," if he had intendedto restrict the scope of the patent to theform set forth. It is inconsistenit for otircritic to assert that the Fiske claim terminat-ing with the words "as set forth" is basic tothe radio-control principle in forms notshown, and yet to deny that the Hammondclaim cited in our paper is not basic to theproximity principle generally, with thewords "as set forth" absentt. In contrast with

1959 1267


the Fiske radio-control patent, the Ham-mond proximity patent did get reduced topractice, we understand, in both media. Itwas not generally known, presumably be-cause no money passed in making it avail-able, and there was no threat of a law suit.

16), 17), and 18). The deForest Audion:We feel that there is need for a formal syl-logism:

AMajor Premise: In writing the words"Audion. This form of detector . . . ,"Marriott had in mind oinly one formof detector, since he used the word"this. "

AMinor Premise: The form to which hereferred as being used in 1912 was un-questionably the triode.

Conclusion: The form to which he re-ferred as being uised in 1906 was there-fore the triode.

Our critic is charging that Marriott was inerror or that he did not express himselfclearly. Since the patent application wassigned in 1906, no one has the right to as-sume that the inventor did niot practice hisinvention in 1906. The fact that it was notpublicly disclosed until 1907 is irrelevant.Strangely, it is we who have to defend anauthor and his paper, when both werepraised by our critic when the paper wasfirst published.

As to the date of the patent, we cor-rected this formally and not by letter to thecritic, because of the criticism, expressed bythe exclamation point, that the Patent Officemay have failed to consider it for a sufficientperiod of time. As far as we have observed,one would have to go back to the original

Bell patent of 1876 to find an importanitpatent which was issued after only threeweeks of consideration.

22) The Lowenstein Designation "IonController": We believe we understood thecoimment as written. An "alias" connotesanother name without change of the objectnamed. Lowenstein's device was a triode,and most certainly not an "audion" com-prising a diode in series with a B battery,which is the onily type of "audion"` men-tioiietl in the sentenice. WVe douibt thatLowensteini's reasons for tusing "ion-con-troller" rather than "grid audionn" were tin-ethical. The word "audion" automaticallysignifies a detector in the patent and tech-nical literature. Such a terminiology was notsufficiently general for onie with the superiorknowledge that a triode was also usefuil foramplification and oscillation uses.

29) Piority of Production of a High-Vacuum Tube. Our critic finally invokes a1931 statement of the Supreme Court in itstermination of a General Electric sulit againstthe de Forest company for alleged infringe-ment of Langmuir's high Xacuum patent1,558,436 of 1925. This seemingly self-con-tradicting sentence was lifted from pertinientcontext, but ulponl conisLulting acceptable re-ports of all three courts involved, we haveparaphrased the final decision as follows."We do niot quiestioni that Langmuir andSweetser prodtuced a 250 v, 5 ma high vacu-um tube 'in which the current was limited byspace charge, substantially independenitlyof positive ionization,' in August, 1912. Butby legal precedent we think that his legaldate of coniception of the patent claims basedupon this work cannot be the date that he

July

did it but rather the date that he knew thathe had done it. We rule that Langmuir'slegal date of conception was in late Novem-ber of 1912. We further stile that Arnold'slegal date of conception was November 14,1912, despite de Forest's stiange willingniessto accept November 1. Therefore in Novem-ber, 1912, Arnold anticipated Langmuir byabout a week in conceiving the suibject mat-ter of the Langmuir claims. But the FederalTelegraph Compainy used a 54 volt amiiplify-inig triode in August, 1912, and a 67' volttriode in Novemaber, thereby anticipatingboth Arnold's and Langituir's legal dates ofconception. Partly uponl this Federal evi-dence, the Langmnuir pateint is hereby and ir-revocably declared invalid anid therefore notinfringed. WN'e feel it highly unnecessary torule on the prior statemlenit that Arnold'sreduction to practice of the Langmuir claimswas on April 25, 1913.' If our interpretationof the Suprenme Court decisioni is acceptable,otur critic must agree that the relephoneCompany work was much later than that ofthe General Electric ini the production ofhigh vacuum tubes.

In conclusion, it appears that our criticrefused further comment on about eightyper cent of the points listed in our first re-buttal. We trust that he would refuse fur-ther commnent on at least eighty per cent ofthe poinits treated again in this second re-sponse to his critiques. We note that his dis-cussions have been offered "in the interest ofmore correct technical history. XVe hope thefotur papers of these discussionis have donemuch to confirm the correctness of the tech-nical history which we set forth in our Sep-tember, 1957 paper.

CorrespondenceLow-Noise Tunnel-Diode Amplifier*

Since Hull first disclosed the dynatron,'negative conductance amplifiers have re-ceived sporadic attention. As early in 1935,E. Wt. Herold pointed out the possibilityof uising negative condtictance for amplifica-tion.2 However, lack of conivenient negative-conductance elements made such amplifiersunattractive. The purpose of this note is toreport some results on a new negative-con-ductance amplifier using a novel semicon-ductor device called a tunnel diode3 whichwas developed by H. S. Sommers at theRCA Laboratories.

The amplifier circuit is shown in Fig. 1.The tunnel diode D, having a capacitance

* Received by the IRE, May 1, 1959. This re-search was sponsored in part by the Electronic Res.Directorate, AF Cambridge Res. Center, under Con-tract AFl9-(604)-4980.

1 A. W. Hull 'Description of the dynatron,n PROC.IRE, vol. 6, p. 5; February 1918.

2 E. W. Herold "Negative resistance and devicesfor obtaining it,' PROC. IRE, vol. 23, p. 1201; Octo-ber, 1935.

3 H. S. Sommers, "Tunnel diodes as high frequencydevices," PROC. IRE, (this issue, p. 1201).

NEGATIVE-f,/ CONDUCTANCE

Cd n

GI Gg INPUT

Fig. 1-Amplifier circuit using a negative-con-ductance diode.

Cd, is energized by a battery Vo through a dcload resistance ro. The resistance ro shouldbe smaller than the negative resistance pro-duced so that stable biasing is possible.The biasing point at which the negative con-

ductance is realized is defined by the com-bined adjustment of the load resistance roand the supply Vs. As shown in Fig. 1, thenegative conductance is shunted by an RFtank which determines the amplifier re-

sonant frequency f1. Cb, a by-pass condensein the tank, should be made as large apossible to prevent parasitic oscillations inthe battery circuit. For stability, the RFload conductance presenited by the combi-nation of the generator conductance G,7 andload conductance GL through a tap trans-formation should be larger than the negativeconductance (G) of the diode. Stable ampli-fication can be achieved only when both dcand RF load conditions are fulfilled.

Expressions for power gaini (gp), band-width (Af), and noise factor (F) of Fig. 1have been calculated; they are

4GQ,GLgp = - __ 2_

(GT (n )2G)2

B = [1 + \/t + 4QL2g4] - 2

_1

_[1 + -QLV]

(if QLg>> 1)

(1)

(2)

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discussion of a history of modern radio-electronic technology · discussion of"a history...

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