This notebook covers the period February-May 1903. All entries are by Edison. The book contains notes and drawings regarding various experimental projects, such as the hardness and composition of phonograph cylinders, x-rays, etheric force and \"xyz rays,\"" and storage batteries. Also included are several pages of notes pertaining to phonograph recording apparatus and to the recording of wireless sound transmissions. A notation from April 1903 indicates that some of this material was recopied into an unidentified \""big book.\"" The pages are unnumbered, and at least one page has been removed from the book. Approximately 60 pages have been used.