This folder contains correspondence and other documents pertaining to the Edison Phonoplex System of Telegraphy. Most of the documents relate to the installation of phonoplex circuits on various American and Canadian railroads. Some of the items deal with the problem of finding suitable batteries, condensers, and other components. Much of the correspondence is by W.S. Logue, field agent for the phonoplex system. Most of Logue's letters are addressed to Edison's secretary, Alfred O. Tate. Tate served as the company's electrician and oversaw its daily business operations. There are also documents addressed to Samuel Insull, manager of the phonoplex system. By 1887, Edison himself was only tangentially involved in phonoplex operations, and very few letters to or from him can be found in this folder.

Approximately 20 percent of the documents have been selected. In the selection of documents, a case study approach has been used. Most of the selected items relate to the Chicago & Grand Trunk Railway and, beginning in late November, the Pennsylvania Railroad. Both of these companies adopted the phonoplex system. Documents pertaining to these two companies have been selected except for routine letters regarding the ordering and shipment of phonoplex components and similar items of a very routine character.

In addition to material concerning the two railroads, the following categories of documents have been selected: documents relating to foreign phonoplex operations; substantive items regarding the system's commercial difficulties and its competition; and one letter addressed to Edison's father, Samuel, concerning a phonoplex contract.

Among the documents not selected are the items dealing with phonoplex operations on the Lehigh Valley, Canadian Pacific, Norfolk and Western, Philadelphia & Reading, and approximately fifteen other railroads. Some of the lines not selected, such as the Lehigh Valley, adopted the system, but most declined to employ the phonoplex due to its cost and its reputed technical problems or because of unsatisfactory trials. In addition, the following categories of documents have not been selected: correspondence regarding the testing of various batteries; routine inquiries from railroad companies; W.S. Logue's personal correspondence; testimonials; documents that duplicate information in selected material.

Related documents can be found in D-87-01 (Bergmann & Co.).