This collection consists primarily of letters exchanged between Edison and Secretary of the Navy Josephus Daniels, along with related correspondence. Many of the typewritten letters are accompanied by drafts in Edison's hand. The two letters in this folder are from April 1917. A letter by Edison from April 11 notes that his preliminary experiments on submarine detection "are so far up to my expectations" and that he has rented a small yacht "which I will use as a Travelling Central Station." Also included in this letter is a reference to his mirror reflection system of communication (Report 17) and a postscript informing Daniels that he has been confined to his home by illness for the past eight days. Additional material regarding submarine detection can be found in Reports 9, 29, and 31 and in Underwater Sound Detection Reports (1917), Naval Consulting Board and Wartime Research Papers.
Edison's efforts to detect submarines by sound are described on pp. 161-164 of Lloyd N. Scott's Naval Consulting Board of the United States.
[X128C27A], Letter from Thomas Alva Edison to Josephus Daniels, April 11th, 1917 1917-04-11
[X128C27B], Letter from Josephus Daniels to Thomas Alva Edison, April 12th, 1917 1917-04-12