[The first paragraph in this note covers all of the Unbound Notes and Drawings for Part I.]
The loose technical notes and drawings constituting this collection cover the years 1873-1878. They relate to a variety of subjects, including telegraphy, electric lighting and power, the electric pen and duplicating press, the telephone, and the phonograph. There are also documents pertaining to various other subjects, such as carbon rheostats, acoustic devices, the tasimeter, and the voltameter. The unbound notes and drawings are organized by year and within each year by subject. Undated notes and drawings, organized by subject, follow the dated material.
The one document in this folder is a drawing by Edison labeled "Case 'H.'" It is probably related to a patent application concerning duplex telegraphs that was filed on April 26, 1873. Case H was amended in May 1873 and again in March 1875 and was issued as U.S. Patent 162,633 on April 27, 1875. Between 1876 and 1878 this patent became the subject of at least three suits involving the Western Union Telegraph Co. against Thomas A. Edison and George Harrington. See the Quadruplex Case volumes in the Litigation Series. Courtesy of Thomas Edison National Historical Park.