This set of drawings covers the years 1876-1878 and is organized according to caveat number. The drawings relate to the telegraph (caveats 74 and 75) and the phonograph (caveats 77 and 80). The numbers 77 and 80 were later assigned to other caveats which are known to have been filed at the U.S. Patent Office. The later version of Caveat 80 can be found in D-78-28 (Patents) in the Document File.