This letterbook, covering the years 1875 and 1877-1878, deals primarily with telegraphy, the electric pen, the phonograph, and the telephone. About 30 percent of the material is in Edison's hand. The remainder is in the hand of Charles Batchelor and William Carman, acting as Edison's secretaries.
The letterbook is divided into two parts. Pages 1-169 cover the period August-December 1875. Most of the correspondence is in the hand of Batchelor and deals with telegraphy, electric pen sales and service, and etheric force. Noncorrespondence, much in Edison's hand, includes: four caveats (autographic press, domestic telegraph, duplex, and quadruplex telegraph); agreements and memoranda concerning sales agencies for, and division of profits from, the electric pen; a list of inventions to be displayed at the Philadelphia Centennial Exhibition; and orders for chemicals and telegraph equipment.
Pages 271-488 cover the period September 1877-April 1878. Most of the correspondence is in the hand of Batchelor and Carman and relates primarily to the design, manufacture, and marketing of Edison's telephone and phonograph. Non-correspondence includes shipping lists for machinery, bills and receipts, and orders for hardware and lumber.
Pages 271-293 are stained with blue ink, apparently as a result of testing duplicating inks. Pages 271-284, which appear to contain doggerel and spurious correspondence, are almost entirely illegible and have not been selected. Page 274 contains the notation: "this is a specimen written with Dextrin with [Sesquichlor?]"
The book contains 488 numbered pages. Approximately 140 pages are missing. Twelve pages that duplicate other pages in the letterbook have not been selected. Courtesy of Thomas Edison National Historical Park.