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 documents in this folder cover the periods February-April 1917 and September 1918. They pertain to Edison's work on a plan to station small boats and destroyers with guns and wireless telegraphs along the eastern seacoast from Maine to Florida in order to detect enemy submarines. Many of the experiments on submarine detection were conducted in Long Island Sound aboard the USS Sachem, and there is reference in Edison's 1918 letter to mechanical problems with the ship's engine "causing unnecessary delays." The letters from 1918 also refer to Edison's work on a "smoke shell"; this work may be related to the oleum smoke bomb experiments discussed in Report 41. The letter by Daniels expresses regret that he was unable to attend the summer camping trip with Edison "and the other good friends who were good enough to invite me." Additional material regarding submarine detection can be found in Reports 27, 29, and 31. Edison's unwillingness to consider the ideas of other inventors in regard to submarine detection is expressed in several letters in Report 26. Courtesy of Charles Hummel.