This letterbook covers the period January-October 1884. Most of the correspondence is by Edison. There is also correspondence by Samuel Insull. Most of Edison's letters are in the hand of Insull, acting as Edison's secretary. The correspondence relates primarily to electric lighting in the United States and abroad. Other letters deal with Edison's laboratory at S. Bergmann & Co., his visit to the Philadelphia Electrical Exhibition of 1884, and the Oriental Telephone Co., Ltd. Also included is an agreement for the sale of the rails used by Edison on his experimental electric railroad at Menlo Park. Among the recipients are the Edison Electric Light Co., the Ohio Edison Electric Installation Co., and the Edison & Swan United Electric Light Co.

The front cover is marked "1884." The book contains 500 numbered pages and an index. Approximately 40 percent of the book has been selected.