Albert Einstein writes to Navara, a Czech mathematician and physicist visiting the U.S. who had developed the concept of a new type of acoustic directional guidance system which he believed could be adapted to torpedos. He had requested Einstein's assistance in approaching U.S. Government authorities about the concept. Einstein contacted Henry Morgenthau, Sr., the father of the Secretary of the Treasury. The present letter confirms the effort bore fruit, roughly translated as ""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..."