This undated notebook was probably used by Edison in 1907 or 1908, but it may have been used as late as 1910. The book contains notes and drawings regarding attempts to increase a cylinder record's volume by adjusting the pressure applied by the reproducer or recording mechanism. There is one entry relating to storage batteries. Also included are several miscellaneous drawings, probably by Edison's youngest son, Theodore. The pages are unnumbered. Only 15 pages have been used.
Courtesy of Thomas Edison National Historical Park.