Elmer Sperry's files on the compound diesel engine and the electric transmission include a number of blueprints and patent diagrams describing his diesel engine and proposed electronic transmission. During the 1920s Sperry collaborated closely with H. C. Snow, an engineer with the Velie Motors Corporation of Moline, Illinois, and the collection includes a complete file of their letters. These records show that in spite of their efforts the diesel project was both a technological and financial failure. Sperry could not develop a working model nor could he raise the capital required to finance research and development in this area. For a while Ford Motor Company, Standard Oil, Baldwin Locomotive Works, and the Illinois Central Railroad expressed interest in Sperry's work but, when research and development did not proceed as rapidly as expected, they quickly withdrew their support.

The records of the W. & A. Fletcher Company consist of fragmentary job files, job account books, engineering notebooks, and a collection of correspondence and miscellany collected by Andrew Fletcher, Jr. A large collection of Fletcher ship and engine drawings is located at its South Street Seaport Museum in New York City. Among the job files are a master list of engines built by Fletcher from 1864 to 1925, and fragmentary correspondence on several orders. The job account books from 1869 to 1917 list cost breakdowns arranged by job. There is a small fragment of correspondence by Andrew Fletcher, Jr., most notably relating to marine turbine technology, and an item from a suit by Fletcher against the International Association of Machinists arising from a strike in 1903. There is also a collection of timetables and annual passes for the many railroads and steamship companies over which Fletcher travelled or with which he had business dealings. There is also a vertical file kept by Andrew Fletcher, Jr., which consists largely of tear sheets from the Nautical Gazette, Marine Engineering, and other trade journals.

There are two anomalous items reflecting Fletcher's role as president of the American Locomotive Works and the Eddystone Ammunition Corp. during World War I. The first is a volume of blueprints for shells, and the second a map of the plants of the Eddystone Ammunition Corp. and the Baldwin Locomotive Works at Eddystone.