Series III, Notes, reference material, and works by Hoopes include typed and printed manuscripts relating to his two books, Early Clockmaking in Connecticut (1934) and Connecticut's Contribution to the Development of the Steamboat (1936), as well as an article, "Special Production Machinery" (1950). There are notes on eighteenth-century patents and collections of patents issued to Andrew C. Campbell and for hook-and-eye closures. Topics in this series include cams, power press design, lock nuts, orreries and clocks, early American inventors, and beauty in design. This series also includes the card catalogs of Hoopes' compiled bibliographic information on early American inventions and physical sciences. Finally, there is Hoopes' manuscript of Technical Americana, a bibliography of works on scientific invention, technology, and invention published prior to 1826, along with the index card file used in compiling the work.