This folder contains copies of outgoing correspondence similar to the material found in the Letterbook Series. Most of the letters cover the period January-October 1888 and pertain to the phonograph, the phonoplex system, electric lighting, and other technical and business interests. Some of the letters deal with the establishment of electric light systems in foreign countries, particularly Japan and Switzerland, and with management changes at the Edison Spanish Colonial Light Co. Other letters relate to the introduction of the improved phonograph in Great Britain and other foreign countries. There are also letters regarding Edison's search for improved batteries, the development of improved condensers at the Edison Machine Works, phonoplex production problems at Bergmann & Co., and problems with electric wiring in the homes in Llewellyn Park. There is also some personal correspondence. Much of the correspondence is by Edison's private secretary, Alfred O. Tate. There are also letters by Charles Batchelor on behalf of the West Orange laboratory and the Edison Phonograph Works.

Approximately 50 percent of the documents have been selected. The following categories of documents have not been selected: routine personal and business correspondence by Edison, Tate, and Batchelor; routine letters from the West Orange laboratory pertaining to accounts, bills, shipping, and miscellaneous orders for equipment and supplies; duplicate copies of selected documents.