These three documents cover the period April-June 1878. Included are two letters to Henry Bentley, president of the Philadelphia Local Telegraph Co., in which Edison discusses improvements in his carbon telephone and proposals to exhibit the phonograph. In addition, there is a letter to Charles H. Winston, professor of physics at Richmond College, in which J. Ambler Smith, patent attorney for the Edison Speaking Phonograph Co., threatens to sue over a patent violation.

Courtesy of the Special Collections, Lehigh University Information Resources.