These documents cover the period December 1875-August 1877, with one additional item from 1869. They consist primarily of letters addressed to the astronomer Henry Draper, a longtime Edison associate. Included is correspondence from Edison discussing Draper's claim to have photographed spectra proving the existence of oxygen in the sun. Also included are letters from George F. Barker, professor of physics at the University of Pennsylvania, pertaining to the Centennial Exhibition in Philadelphia, Edison's carbon telephone and discovery of "etheric force," and other matters. The item from 1869 is a report of the Executive Committee of the National Telegraph Co. on George Little's automatic telegraph system. During the early 1870s, Edison made several improvements in the Little system while under contract to Daniel Craig, a businessman with financial interests in the National Telegraph Co.
An online finding aid to the archival collection is available. Courtesy of The New York Public Library, Astor, Lenox, and Tilden Foundations.