This notebook was used by Edison in January-February 1916 for notes on experiments to improve the composition of disc record blanks and the varnish surfaces applied during the transfer process. Included are notes describing experiments numbered from 139E to 185E in which the ingredients for record blanks and record varnishes are varied. Also included is a small group of experiments on varnish compounds, along with several lists (called "testers' designations") of flaws observed in record blanks. Additional entries summarize the results of the numbered experiments, as well as relevant information from earlier notebooks. The front cover is labeled "1916 #4." The pages are unnumbered. Approximately 140 pages have been used. Courtesy of Thomas Edison National Historical Park.