This notebook covers the period February-April 1910. All entries are by Edison. It is the first of three books that contain notes and drawings regarding the development of phonograph recording and reproducing apparatus. A notation in the second book indicates that much of this work was conducted at Edison\'s laboratory at Fort Myers, Florida. In an entry dated April 9, 1910, Edison notes that \"the talking is the clearest & best I have ever heard on the phonograph Bar none\"" and that \""this is the Recorder par excellanc to work with--.\"" Several entries indicate the involvement of Alexander N. Pierman and Frederick P. Ott. At the end of the book are cost calculations for storage batteries and for cement production. The front cover is marked \""Phonograph No 1 Feb. Mch. April. 1910.\"" The pages are unnumbered. Approximately 160 pages have been used.