This letterbook covers the period February 1888-August 1889. Most of the correspondence is by Charles Batchelor, superintendent of the laboratory, and by C. E. Sullivan, storekeeper. There are also a few letters by Edison and by Arthur E. Kennelly, chief electrician. Most of the letters are routine items pertaining to the ordering of supplies and equipment for the West Orange laboratory. Only five documents have been selected: three letters by Kennelly concerning the effects of magnetism on watches; and two letters regarding the construction of a picket fence around the laboratory. The front cover is labeled "Credit Book." The spine is stamped "Letters." The book contains 494 numbered pages. Pages 117-494 are unused.