Discussion of "A History of Some Foundations of Modern Radio-Electronics Technology" Page 1263

waterborne carriers of explosives, Hammond was able to grant Sperry an exclusive license for developing the airborne field under claims dominating the change of course of an aeroplane under radiant energy control, such as the following from patent 1,568,974:

“29. In combination, a self-stabilizing, self-steering aircraft, and means comprising a radiant energy transmission system for causing said aircraft to make any desired turn in azimuth at any point in its flight.”

“30. In combination, a self-stabilizing, self-steering aircraft, means comprising a radiant energy transmission system for causing said aircraft to make any desired turn in azimuth at any point in its flight, and means for automatically banking the craft while turning.”

As a result of the Hammond-Sperry agreement of 1925, all later radiant energy airborne-guided missile-type equipment produced by Sperry involving a change of a stabilized course, carried Hammond patent numbers. Pre-World War II radio-guided aeroplanes came to be known as Hammond-Sperry Drones.

Additionally, it is to be noted that automatic pilot systems commercially developed for passenger planes with a pilot in attendance are covered by the basic patents of Hammond filed in 1913, such as that cited in the discussion of Section II-9 above.

Therefore we submit that Hammond, and not Sperry, was the true pioneer in the development of the “automatic pilot” for waterborne craft, and that patentwise, the invention is dominated by patents that went exclusively to the U. S. Government in 1932; that Hammond’s gyro-pilot ideas applied in the waterborne field were also applicable in the airborne field, regardless of whether there was a human pilot also available, or whether the craft was radio-controlled; that in the explicit field of radiant energy control of airborne torpedoes in which he was not obligated to the Government, Hammond granted the Sperry Company exclusive rights which it acknowledged and exercised in pre-World War II aerial torpedoes and the like. Hammond pioneered the “automatic pilot” and both Hammond and Sperry produced it. Sperry²⁴ did not hesitate to regard Hammond as a personal friend as well as an associate in this development.

13) Critique. “But ahead of Tesla, apparently, were the two British inventors, Wilson and Evans. . . . The receiving control electromagnet is made dependent for its operation upon the receipt of both channels. . . .”

Rebuttal. The cited patent in Fig. 7 shows such a control magnet. However, there does not seem to be any patent claim specific to this manner of practicing the invention, nor to any security advantages. The Wilson and Evans arrangement would be subject to interference on a “channel” intermediate between the horizontal and vertical polarization “channels”: the Tesla system would not so readily be forced by any single channel, since in the Tesla system, the word “channel” is in the usual frequency sense. It is the Tesla system that is the background of the Hammond single-shot FM system of security used on the Natalia.

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

Rebuttal. Such a system is irrelevant to the discussion. Hammond’s system was simplex, depending upon the reception of both ends of the transmitted spectrum to establish a single control signal. The de Forest system, apparently, was diplex, with one end of the spectrum for conveying one message and the other end for another independent message. There was no cooperative action between two channels to produce a single signal as in the Hammond security system and as in modern FM reception.

15) Critique. “. . . the claim is for a torpedo, meaning in water. . . .”

Rebuttal. The words “as set forth” do not appear in the claim, therefore the claim is not limited by the drawings and specifications, but only by the allowable breadth of the words “torpedo” and “energy.” We consider the word “torpedo” applies to aerial torpedoes, and that “energy” applies to electromagnetic energy. Note that contrary to the statement of our critic, the word “fuse” is absent from our paper. While the “proximity fuse” principle may apply to airborne devices, the “proximity” principle applies to both air- and waterborne devices. Neither we nor presumably our critic are in a position to know whether or not the proximity principle, in fact, has been applied in both media.

III. THE TRIODE TUBE

16) Critique. “The quotation is correct, but the assumption that it referred to the triode rather than the diode, as of 1906, is in error.”

Rebuttal. On the contrary, our assumption that it applied to the triode both in 1906 and also later is not in error. The Marriott reference in its entirety on this point is:

“5. Audion. This form of detector was used to some extent as early as 1906, but apparently in small numbers until about 1912 when the amateurs became active in its use, and within the last year or more it has been used to some extent by the Government.”

Now our critic later states, “It was about that time that the grid audion began to come into some use, ‘but apparently in very small numbers’ as Marriott said.” Since Marriott referred to “this form of detector,” and since the form of detector as of 1907 was the grid audion form, as our critic admits, it follows that Marriott was referring to the detector of 1906 as a triode. Our critic does not openly say that the Marriott statement was in error, but does say that we were in error in interpreting it. Our critic, in his first printed discussion of the Marriott paper in the Proceedings,²⁵ failed to challenge the Marriott statement in this matter, as he must now do.

17) Critique. “The grid triode appears to have been invented toward the end of that year or the beginning of 1907.”

Rebuttal. The patent application covering the invention of the grid triode²⁶ was signed by de Forest on December 21, 1906. Therefore, since de Forest undoubtedly used the grid triode in 1906, it appears that the Marriott statement as to dates is just as correct as our interpretation of it.

18) Critique. “It . . . issued as a patent February 18, 1907. . . . (There was no time lost in those days!)”

Rebuttal. The grid triode patent referred to issue February 18, 1908. The parenthetical statement shows that the error could not have been due to any typographical error of the printer.

19) Critique. “Among those small users, to the writer’s knowledge, were a few amateurs. . . . The writer, with two other amateurs . . . attended de Forest’s Brooklyn lecture. . . .”

Comment. Our critic, according to “Who’s Who in Engineering,” joined the engineering staff of the Telephone Company in 1910. There was, therefore, at least one member of the Telephone group who knew of the de Forest triode two years before the Telephone Company, as our critic later states, learned about it in 1912.

20) Critique. “The grid audion detector continued for some years solely as a detector.”

Comment. The critic here lapses into the early usage of “Audion detector” as meaning a triode tube regardless of the use to which it was put in circuitry.

21) Critique. “But they do not tell the whole story and give the impression of Hammond’s role having been more than it was.”

Rebuttal. There was no need of telling the whole story. The prior attempts at developing the triode were recorded in the first and last parts of the paragraph, showing that Lowenstein still, in 1912, had a lot more to develop. Hammond’s immediate interest was the procurement of a better type of “relay-operating rectifier-detector,” and in this branch of the work, Lowenstein may have been a true consultant. At least, he never changed the words “Consulting Engineer” on his letterhead²⁷ when writing about any phase of the ion controller project. Hammond’s role quickly became that of an unsecured creditor, but with paper rights in exploiting the triode developments. On the basis of personal friendship, a settlement of financial matters was made with Lowenstein about three months before his sale of the grid bias patent to the Telephone Company, at such a figure that the entire amount received from the sale went directly to Lowenstein as a clear profit. The Hammond role was not exaggerated in the paper.

22) Critique. “The term ‘controller’ or ‘ion controller’ was Fritz’s alias for the name ‘Audion’ which de Forest had bestowed upon Fleming’s tube upon adding to it the ‘B’ battery.”

Rebuttal. This is greatly in error. The Lowenstein “ion controller” was a triode, and not a Fleming diode. Our critic may have confusedly substituted a battery ex-

²⁴ Letter of Sperry to G. A. E. Lundell, October 21, 1926.
²⁵ L. Espenschied, “Discussion,” Proc. IRE, vol. 5, p. 196; June, 1917.
²⁶ U. S. Patent 879,532 to L. de Forest.
²⁷ Letter of Lowenstein to Hammond, November 13, 1911.