This letterbook covers the period May 1886-April 1887. Most of the correspondence is by Insull. Some of Insull's letters are in the hand of John F. Randolph, acting as Insull's secretary. The correspondence relates both to Edison's business interests and to Insull's personal affairs. Included are letters about Edison Electric Light Co. stock, Edison's foreign telephone interests, and the commercial application of the phonoplex telegraph system in the United Kingdom. Among the recipients are George F. Barker, Joseph Insull, and P. B. Shaw. The spine is labeled "1886" and is stamped "Letters." The book contains 293 numbered pages and an index. Pages 77-293 are blank. Approximately 30 percent of the documents have been selected.