This pocket notebook is a continuation of PN-18-09-10.2. The one dated entry is from October 1918. The book was used by Edison for experiments on sound detection devices to locate enemy submarines. The experiments were discontinued after the signing of the Armistice on November 11, 1918. Among the employees mentioned in the book are experimenters Isidor (Jerry) Chesler, Newman Henry Holland, and Frederick P. Ott. The front and back covers are both marked "War 2." The pages are unnumbered. Approximately 30 pages have been used.