Analog Computing Component - 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 to assure high accuracy and durability. It has two stacked balls, held by stiff springs, between a disk and cylinder, each made of hard steel. The balls are held in place by pairs of small rollers in a carriage. This design permitted the carriage to move even when the disk was not moving, a feature that is necessary when integrating with respect to a variable other than time. From about 1915 into the 1940s, Ford's integrators were used by the U. S. Navy in devices for aiming guns on ships.

The frame is painted white.

A mark on the side of the frame, facing up, reads: 629823. A plasticized tag reads: #78b. The object is described in the accession file as a “4” Integrator cast frame construction of a design later than Item No. 7 used on Range Keepers and Computers.” Item No. 7 is 1982.0751.07.

Objects 1982.0751.35, 1982.0751.36, and 1982.0751.37 are stored together in a wooden box lined with fabric that has a black handle. A tag on it reads: #78 Integrators 78a, 78b, 78c. The handle has two paper labels attached to it with string. One reads: Grand Central Terminal (/) Red Cap Service (/) Serial Number 35773 Red Cap Number 137. The other reads: No. 83583 Q.

Compare 1982.0751.06 and MA.319517. For further background and references, see 1982.0751.07.

References:

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

Accession file.

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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