This letterbook covers the period December 1884-September 1885. Many of the letters are by Edison. There is also correspondence by Samuel Insull. Most of Edison's correspondence is in the hand of Insull, acting as Edison's secretary. The correspondence relates to a variety of subjects. Included are letters about central stations, foreign electric railroad patents, and patent infringement suits brought by the Edison Electric Light Co. Other correspondence concerns the Edison Ore Milling Co., Ltd. and the English telephone. There are also several letters written by Insull to Edison during Edison's stay in Florida. Among the recipients are S. Bergmann & Co., the Compagnie Continentale Edison, Charles H. Coster, A. A. Cowles, the Deutsche Edison Gesellschaft, and Francis R. Upton. The front cover is marked "1885." The spine is stamped "Letters." The book contains 500 numbered pages and an index. There are also numerous groups of unnumbered pages inserted into the book between the numbered pages. Approximately 40 percent of the book has been selected.