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. Edison himself was only tangentially involved in phonoplex operations, and very few letters to or from him can be found in this folder.

Approximately 10 percent of the documents have been selected. The case study approach begun in 1887 continues for the Pennsylvania Railroad; substantive items relating to the operations of the phonoplex on that railroad have been selected. In addition, the following categories of documents have been selected: substantive items regarding sales strategies, competition with Western Union, and Logue's role as field agent for both the phonoplex and the Edison Manufacturing Co.; correspondence about technical problems, indicating substantive involvement by Arthur E. Kennelly, chief electrician at the West Orange laboratory; and an advertising circular issued by the Edison Phonoplex System.

The following categories of documents have not been selected: most documents dealing with phonoplex operations on other railroads; letters of inquiry from railroad companies; Logue's accounts and personal correspondence.

Related material can be found in D-90-01 (Battery), D-90-02 (Bergmann & Co.), and D-90-27 (Edison Manufacturing Co.).