This letterbook covers the period April-June 1891. Most of the letters are by Alfred O. Tate. There is also correspondence by Edison, Thomas Maguire, John F. Randolph, and E. W. Thomas. Many of the letters relate to Edison's work on an improved phonograph and to legal and financial dealings among the various phonograph companies. Some of the legal correspondence concerns the litigation involving Edison, the Edison Phonograph Works, and the Edison Phonograph Toy Manufacturing Co. In addition, there are numerous letters pertaining to the business of the New Jersey & Pennsylvania Concentrating Works, including the leasing of mining properties and Edison's investments in that company. Included also are documents concerning the company's relations with the Edison Phonograph Works, which supplied it with ore-milling machinery and equipment. There is also correspondence relating to the Edison Manufacturing Co. at Silver Lake, N.J. and to the manufacture and marketing of the improved Edison-Lalande primary battery. Other letters deal with electric lighting and with the establishment of billing procedures for experimental work done at the West Orange laboratory for the Edison General Electric Co. The front cover is marked "1891." The book contains 700 numbered pages and an index. Approximately 25 percent of the book has been selected.