These two documents relate to Charles A. Young of Princeton University, who conducted a series of efficiency tests on Edison's generators and lamps during the early 1880s. Included is a May 1881 letter from Edison requesting Young's assistance in fighting patent infringements. In addition, there are notes concerning a test made by Young on an Edison dynamo in April 1882.
An online finding aid to the archival collection is available. Courtesy of Dartmouth College Library.