These documents, which cover the years 1879-1930, consist primarily of correspondence, along with a small number of other unbound items such as agreements and lists. Approximately 100 documents, both incoming correspondence and copies or transcriptions of Hammer's outgoing letters, have been selected from Series 1 and 2 of the archival record group. More than half of the letters are either to or from Edison, many concerning Hammer's work for Edison at Menlo Park and in Europe. Other correspondents include Edison associates Charles Batchelor, Edward H. Johnson. Theodore Puskas, and Francis R. Upton. In addition, there is correspondence from the 1920s with former laboratory assistant Francis Jehl regarding his recollections of Edison and the Menlo Park laboratory and with industrialist Henry Ford and his secretary, Frank Campsall, concerning the transfer of Hammer's collection of Edisonia to the Ford museum. A three-page undated list of Menlo Park laboratory employees precedes the dated correspondence. The last document, dating from December 1930, is a letter from Hammer requesting Edison to send "our old friend," World War I hero Alvin C. York, a combination phonograph-radio. Courtesy of the NMAH Archives Center.