This notebook is a continuation of N-17-06-08. It was used by Edison in June 1917 to record research performed for the U.S. Navy during World War I. This work was probably done in connection with Edison\'s attempts at aiding submarine detection. Some of the entries bear notations by Isidor (Jerry) Chesler. Included are diagrams and descriptions of experimental amplifiers for detecting sounds, along with notes regarding their performance. The components involved include audions, induction coils, batteries, condensers, telephone receivers, and mirror galvanometers. One set of entries describes experiments to ascertain the cause of \"flickering\"" in audion circuits. The experiments are continued in N-17-06-28.The front cover is labeled \""U3.\"" The book contains 100 numbered pages; page 100 is blank."