This letterbook covers the period December 1883-January 1884. Many of the letters are by Edison. There is also correspondence by Samuel Insull and Alfred O. Tate. Most of Edison's letters are in the hand of Insull or Tate, acting as Edison's secretary. Included is correspondence relating to the purchase of supplies and equipment and to the payment of overdue bills. Some of the letters pertain to central stations in South America. There are also cost and profit estimates for central stations in Danbury, Connecticut; Louisville, Kentucky; and Haverstraw and Poughkeepsie, New York. Among the recipients are S. Bergmann & Co., the Electric Tube Co., and W. D. Rich. The spine is labeled "1883-1884" and is stamped "Letters No.4. T. A. Edison Central Station Construction Department." The book contains 487 numbered pages and an index. Approximately 20 percent of the book has been selected.