Ford Instrument Company Ball & Disc Integrator

Instruments for finding the area bounded by curved lines (integrators) date from the nineteenth century. This twentieth century example is based on a mechanism invented by British engineer James Thomson and used by his brother William (later Lord Kelvin) in constructing the first harmonic analyzer in 1876. The object shows modifications and refinements made by the American inventor Hannibal Ford. It consists of a metal mechanism held in an aluminum frame painted white that is attached to a black bakelite base. The mechanism includes two (rather than just one) hardened steel balls that roll against one another. The bottom ball is turned by a disc on the bottom driven by an input gear. The top ball drives a roller.

A metal tag on the front of the base reads: 2 ½ Inch (/) BALL AND DISK (/) INTEGRATOR (/) Presented by (/) FORD INSTRUMENT COMPANY (/) DIVISION OF SPERRY RAND CORPORATION.

Ford's integrators were used in devices for aiming guns on ships of the U.S. Navy from about 1915 into the 1940s. The company merged with Sperry Corporation and, in 1955, became a subdivision of the newly established Sperry Rand Corporation. This object dates from after the establishment of Sperry Rand and before the donation of the object to the Smithsonian in 1961. A leaflet describes “Ford Precision DBR Integrators.” Here the acronym DBR is defined to mean “DIsk-Balls and Roller Integrator.”

Compare 1982.0751.06 and 1979.0751.36.

References:

“Ford Precision DBR Integrators,” no date.

Accession file.

A.B. Clymer, "The Mechanical Analog Computers of Hannibal Ford and William Newell," Annals of the History of Computing, 15, #2, 1993, 19-34.

K.C. Epstein, Analog Superpowers: How Twentieth Century Technology Theft Built the National Security State, Chicago and London: University of Chicago Press, 2024.

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