Discussion of "A History of Some Foundations of Modern Radio-Electronics Technology" Page 1253

Critique by Lloyd Espenschied *

In tracing their own inventing over the years, Hammond and Purington¹ recall interestingly the evolution of our modern art from the time of spark wireless telegraphy as of about 1910. But they give the impression that their inventing played a more foundational role than was the case. With the possible exception of Fritz Lowenstein’s realization of the amplifier out of de Forest’s grid audion detector, which appears to have been conceived before he became associated with Hammond, it may be said that the roots of our modern technology trace back generally to sources other than the Hammond Laboratory. Actually, Hammond’s work was conducted in secret, as the authors aver, while speculative patents, filed prolifically, were long held in the Patent Office. Meanwhile the advance rolled on, with its literature accumulating, generally oblivious of the Hammond group. Hence claims made in the paper to “firsts” and to the establishment of “principles” are in need of amendment, as discussed below. The writer regrets having to turn critic, for he welcomed the rendering of the Hammond story. As it is, the paper will contribute more to technical history by calling for additional evidence. We follow the sections of the paper beginning with Section II.

THE RADIODYNAMIC TORPEDO (SECTION II)

Hammond is best known for his long pursuit of the problem of directing torpedoes by radio control. As still earlier pioneers in this field, mention is made in the paper of a pair of British inventors and of N. Tesla. But singularly omitted from mention is the one who received from the U. S. Patent Office the underlying claims, one of which reads:

The combination with a source of electrical waves or disturbances of a moving vessel or vehicle and mechanism thereon for steering or operating the same, and controlling apparatus adapted to be actuated by the influence of the said waves or disturbances at a distance from the source, as set forth.

This is Patent No. 660,155, one of a pair, means and method patents, granted to Lieutenant (later Admiral) Bradley A. Fiske, October 23, 1900. Fiske had filed only a few months after Tesla in 1898 and was able to swear back of Tesla and obtain the primary claims. In 1912 Hammond wrote from Washington, D. C., a letter² inquiring about this patent, saying “I am very much interested in Patent No. 660,155 . . . .” and going on to observe: “This is the first record of any kind which completely covers the art of wireless control of mechanisms.” Thus, one wonders why Fiske is not cited as a pioneer, or the pioneer, in the present paper. In the

summer of 1915 Hammond was selling to a Congress worried by the European war then raging, his system of wireless control of torpedoes. Fiske became concerned lest his patents be infringed and issued a public statement explaining how he came to make the invention, and observing that, “Mr. John Hays Hammond, Jr. has done splendid work based on my original patent.”³ In his autobiography of 1919 Fiske wrote, “ . . . I do not know of Mr. Hammond ever giving me credit for having suggested the plan originally, or of his disclaiming the credit given him for it in many accounts of his achievements.”⁴

Of course it was quite impossible for any of the early inventors to get very far on this problem, so crude was early radio; and even after the revolutionary high-vacuum tube came along, to reach an underwater vessel with control signals was most difficult. Two World Wars have now occurred with no military use of the radio-controlled torpedo; it is just as well, except for the futile expenditure of technical effort and public money.

Among the “principles” claimed to have been developed in the 1910–1914 period is that of the automatic stabilization of the course of a torpedo by means of the gyro.⁵ Yet one reads in the Encyclopaedia Britannica of 1910–1911, eleventh edition, under the article on “Torpedo,” of gyrocontrol trials in 1896 which “demonstrated the feasibility of accurately and automatically steering a torpedo in a direct line by this means,” and of the Whitehead firm having “produced the apparatus which is fitted to every torpedo made.”

Under the subheading “Automatic Course Stabilization” it is said, “ . . . in 1912, the Sperry Gyroscope Company and the U. S. Navy were developing a precise and reliable motor-driven gyrocompass with remote repeaters.” This development is understood to have been undertaken by Sperry alone, the Navy adopting the system upon its appearance in 1911. The paper continues: “The Hammond Laboratory engineered the modification of one of these devices so that the repeater controlled not a compass indicator, but the operation of a steering engine.” This modification was rather obvious since the idea of steering a ship automatically from a magnetic compass was old. This connecting of a Sperry gyro to a steering gear instead of to a compass indicator is referred to as the “automatic pilot principle,” as if the automatic pilot originated with Hammond.

This section of the paper, under the previously mentioned subheading “Automatic Course Stabilization,” is made more confusing by the inclusion in it of a reference to

three Hammond patents,⁶ as if these patents cover course stabilization and the automatic pilot. They do not; they apply only to the application thereto of radio control. In fact, the arrangement shown for combining gyro and steering engine is unserviceably crude—the control is intermittent rather than continuous, through declutching, and there is no means for restoring the rudder to normal after a turn, i.e., repeat back, so necessary for an operable automatic pilot. Thus, the three patents added nothing to automatic course stabilization per se and their inclusion at this point in the text is misleading.

The man who pioneered and produced the automatic pilot was Elmer A. Sperry. His early progress is described in a comprehensive paper of 1913. “Perhaps the most interesting of all the apparatus which we have developed is the aeroplane stabilizer, . . . .” the section on this subject begins. It was applied to a Curtiss Hydroplane, and is pictured in Figs. 28 and 29.⁷

Under the subheading “Security of Radio Control,”⁸ Tesla is credited with having “proposed a security system based upon the coincidental transmission on two channels: a forerunner of the ‘and’ principle of modern computers.” But ahead of Tesla, apparently, were the two British inventors, Wilson and Evans, mentioned earlier in the paper. Their U. S. Patent No. 663,400 of 1898–1900, shows coincidental transmission over two channels. Two short-wave Hertzian dipoles disposed mutually perpendicular with a similar pair for receiving, provide two channels by polarization. The receiving control electromagnet is made dependent for its operation upon the receipt of both channels, whereby it appears Tesla was limited to two different frequencies.

A so-called Hammond system which uses in a conjoint manner the familiar marking and spacing waves of the Poulsen arc transmitter is described. Later in the paper this is made the basis of claims to FM. But de Forest, then of the Federal Telegraph Company, who installed Hammond’s arc equipment in 1913, already had devised what he called “ . . . a diplex system of telegraphy, using a high-speed chopper.” It “automatically changed the wavelength of the transmitter from A to B a great number of times per second, so that both the A and B operators could dispatch their messages. . . .”⁹ Hence the Hammond claim to “ . . . the first example of security systems using both time and frequency diversity” appears to have been an adaptation to a slow “security” operation of de Forest’s diplex.

* 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 Western Electric Co., 463 West St., New York, N. Y.
³ The 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. Y., p. 232; 1919.
⁵ Footnote 1, p. 1192.
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 Autobiography of Lee de Forest,” Wilcox and Follett Co., Chicago, Ill., p. 277; 1950.