This notebook was used by Edison during the period April-May 1912. It contains notes on phonograph recording experiments, including information on various recorders, horns, and recording arrangements. The entries describe three modifications of the "regular" recorder: a "Deep Recorder," a "Sensitive Recorder," and a "NY Recorder." Included are Edison's evaluations of the quality of recording in the experiments made with each recorder under a variety of conditions. Also included are drawings of modified recording diaphragms. Inserted into the book are several pages of loose notes and drawings by Edison and Alexander Pierman from the period May-August 1912 pertaining to various aspects of experimental recording equipment. The inside front cover is inscribed "Mr. Piermanís Tests." The pages are unnumbered. Approximately 75 pages have been used. Courtesy of Thomas Edison National Historical Park.