This notebook was begun in 1873 and contains only one dated entry, for April, 1874. Most of the notes and drawings are by Edison. There are also a few entries by Charles Batchelor, including notations of hours spent on experiments. The material relates primarily to diplex, automatic, and chemical telegraphy. The front cover has been labeled by Batchelor: \"Experimental Researches Vol. 1 Edison\'s Laboratory.\"" The book contains 148 numbered pages.

Blank pages: 108-117, 120-148. Missing pages: 1-24."