This notebook contains drawings and notes by Thomas Edison, probably from 1867, and personal accounts of Edison's father, Samuel, with one dated entry from August 1869 and other dated entries from January 1870 to June 1871. Almost all of the material by Thomas Edison is in ink and consists of 16 pages of drawings of telegraph apparatus or arrangements; two lists of books, mostly on telegraphy and electrical science; an unfinished table about relative electrical conductivities; and sketches of some simple geometric elements. The drawings include copies of telegraph repeater designs, some of Edison's own designs for repeaters, two duplex systems, and various relays. One book list and the geometric elements are widely separated by blank pages from the other material by Thomas Edison. The Samuel Edison accounts are in pencil and most of them appear in two groups, about 10 pages at the beginning of the book and about 20 pages at the end. The cover is marked "Memoranda." Approximately 60 pages of this unnumbered book have been used; about 30 pages have been removed from the book. Many of the pages are completely loose and their original order is unclear. Courtesy of Thomas Edison National Historical Park.