Analog Computing Component - Planetary Gear and Dials


This aluminum object has one round face painted black. The outside ring of this face has a scale of unequal parts marked from .5 to 10 and then Ꚙ [infinity]. Rotating the dial inside this ring rotates two gears attached to a cylinder that rises from the dial. The cogs of these gears link to a single gear below them that is smaller in radius but higher. A mark on the frame for this smaller gear reads: 3716655. Between the gears that rotate with the dial plate is a second gear with larger diameter that is attached to the dial ring by four rods. A black mark on this gear reads: 113T-. Near the top (or back) of the mechanism is another ring.

Ford Instrument Company designed and produced gears like this one to be part of mechanisms that carried out calculations (analog computing devices). According to the accession file, this is a planetary gear with dials, “a two speed dial assembly for reading data. Used on MK I computer.”


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.

Date Made: ca 1940

Maker: Ford Instrument Company

Location: Currently not on view

Place Made: United States: New York, Queens, Long Island City

Subject: Mathematics


See more items in: Medicine and Science: Mathematics


Exhibition Location:

Credit Line: Ford Instrument Company, Division of Sperry Rand Corporation

Data Source: National Museum of American History

Id Number: 1982.0751.09Catalog Number: 1982.0751.09Accession Number: 1982.0751

Object Name: analog computing component

Physical Description: aluminum (overall material)Measurements: overall: 6.8 cm x 9.2 cm x 9.2 cm; 2 11/16 in x 3 5/8 in x 3 5/8 in


Record Id: nmah_690593

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