Beschreibung:

EINSTEIN, ALBERT. Five typed letters signed ("A. Einstein") to Frantisek Navara in German, one letter with three-line autograph postscript, Nassau Point, Peconic, Long Island, N.Y., 3-28 August 1938. Together 5 pages, 4to, minor browning (especially to the letter of 22 August), not affecting legibility . EINSTEIN HELPS THE INVENTOR OF A HOMING TORPEDO An interesting series of five letters to Navara, a Czech mathematician and physicist visiting the U.S. Navara had developed the concept of a new type of acoustic directional guidance system which he believed could be adapted to torpedos. Einstein's replies are initially somewhat indifferent, then intrigued but mildly skeptical and finally, enthusiastic and helpful. 3 August 1938: "The most efficient way of proceeding might be for you to send me a clear diagram of your invention. (Absolute discretion assured.) If I get the impression that the idea holds promise, I would be very happy to recommend you to a local official..." 16 August: "The principle of your discovery is quite ingenious. I foresee however a practical difficulty that seems to me almost impossible to overcome. The primary sonar transmitter will directly affect the sonar receptor through the body of the torpedo, in fact 1000 times more strongly than through the waves reflected from the target. I doubt that it will be possible to precisely counterbalance this direct effect upon the receptors in order to avoid its causing the torpedo to turn ... It would seem possible to me to give up the idea of having the torpedo equipped with its own sonar transmitter and instead to rely exclusively on the acoustic waves in the water that will be sent back by the target itself. However, these will not be strong enough to activate a directional device. One would have to try to utilize the differences in phase as an activating principle. It seems equally questionable whether this can be carried out in practice. In any case, for the time being, I do not consider the outlook for your project to be sufficiently favorable for me to support it." 17 August: "Now I believe that your efforts promise to bear fruit, since the source of sonar emissions is now the ship to be torpedoed..." Einstein here spells out a series of specific technical recommendations. "If you could bring yourself to follow this plan, you can call on me at any time! -- For I am convinced of its feasibility." 22 August: "Following your latest observation about alternating the initialization between the transmitter and the receptor, I also find your plan worthy of recommendation. I have asked Mr. Henry Morgenthau senior, the father of the Secretary of the Treasury, to recommend you to the appropriate officials in the Navy. It would therefore be a good idea for you to call on Mr. Morgenthau..." 28 August: "Please find enclosed a letter of recommendation from Mr. Morgenthau to the Secretary of the Navy, Mr. Swanson. It would be advisable to send a friendly thank you to the old gentleman..." The exchange is intriguing in light of Einstein's ackowledged pacifism prior to the rise of Hitler's regime; it pre-dates Einstein's famous letter to Roosevelt regarding military use of nuclear power (September 1939). Armed with Einstein's recommendation, Navara met with officials of the Navy Department in Washington later in 1938 and passed on the idea behind his invention, for which he sought no reward, and insisted his name not be connected with it. He returned to Czechoslovakia, shortly over-run by the Nazis, and kept Einstein's letters securely hidden. All are hitherto unpublished. (5)