This letterbook covers the period January 1881-August 1882. Most of the correspondence is by Edison. There is also correspondence by Samuel Insull and Richard N. Dyer. Most of Edison's letters are in the hand of Insull or John F. Randolph, acting as Edison's secretary. Included is correspondence relating to Edison's patents, electric lighting in Europe, and the application of the phonograph to telephony. There is also a cost estimate for an electric railroad similar to the one constructed by Edison at Menlo Park. Among the recipients are the Edison Lamp Co., the Edison Electric Light Co., the Edison Machine Works, and Sherburne B. Eaton. The spine is labeled "1881-1882" and is stamped "Private Letters 6." The book contains 963 numbered pages and an index. Approximately 30 percent of the book has been selected.