This folder contains correspondence and other documents relating to the construction and installation of central stations. Most of the documents deal with technical problems, for which the engineering department had responsibility. There is also some material concerning the ordering of supplies. Documents pertaining to the engineering problems of one specific station can be found in the folder for that station. Many of the documents in this folder are by William S. Andrews, chief electrical engineer; Frank J. Sprague, electrical consultant; W. D. Rich, superintendent of construction; and Thomas P. Conant, wireman and technician. Many of the letters by Andrews are partially illegible due to water damage. Some of Rich's correspondence is also faint and may be difficult to read. Among the undated items at the end of the folder is a series of questions and answers pertaining to steam boilers, engines, and meters, which was designed to be given to prospective employees. A related set of questions and answers can be found in the Company Records Series.

Approximately 80 percent of the documents have been selected. The following categories of documents have not been selected: routine correspondence regarding orders and employee expenses; duplicate copies of selected documents.