This undated notebook is a continuation of N-17-06-28. It was used by Edison, probably in July 1917, to record research on the measurement and amplification of sound for the U.S. Navy during World War I. Included are notes on the construction of mirror galvanometers and other measuring devices, numbered U18 and U24-U35, as well as an experiment with a "silver carbon telefone." Additional entries made on board ship near Sandy Hook, New Jersey, relate to Edison's tests of experimental amplifying equipment for direction finding and detecting sound under water. The notes indicate that Isidor (Jerry) Chesler and Absalom M. Kennedy assisted Edison in this work. The front cover is labeled "U.5." The pages are unnumbered. Approximately 20 pages have been used. Courtesy of Thomas Edison National Historical Park.