This letterbook covers the periods May 1902-June 1904, May 1905, and December 1910. It contains some outgoing correspondence by Edison, but most of the letters are by Walter S. Mallory, John V. Miller, and John F. Randolph. The letters deal with the capitalization of MECNJ and with mining leases in the Sudbury district of Ontario. Included is correspondence pertaining to Edison's agreements with MECNJ and the Edison Storage Battery Co. Several items relate to the diamond-drilling outfit. One letter concerns estimates of U.S. Steel Corp.'s requirements for nickel.
The label on the front cover contains the following notation: "Mining Exploration Company of New Jersey From May 3rd 1902 To Dec. 16, 1910." The book contains 995 numbered pages and an index; it has been used to page 246. Approximately 10 percent of the book has been selected. A few unselected items concern attempts to find an American substitute for the magnetometer produced by Thalén & Tiberg of Sweden.