Grant Calculating Machine, Centennial Model


In 1876 the Massachusetts inventor and entrepreneur George B. Grant displayed a calculating machine similar to this one, as well as a difference engine of his design, at the Centennial Exhibition, a world’s fair held in Philadelphia.

The barrel-type, non-printing machine has a rectangular wooden base, cut out to allow for the motion of a set of wheels that rotates on a shaft near the bottom. This shaft is linked to a larger upper cylinder by gears so that the wheels and the cylinder turn simultaneously when a handle at the right end of the upper cylinder is rotated. The frame for the instrument consists of hollow discs at opposite ends of the base, which are connected to the two shafts already mentioned, and a third shaft which carries a set of eighteen spring claws that link to the gears of the wheels.

Part of the upper cylinder has a metal collar that can be set at any of eight positions on the cylinder with a locking pin. This collar supports eight movable rings. Each ring has an adding pin and a stud on it which may be set at any of ten positions, labeled by the digits from 0 to 9. The lower cylinder has one group of ten recording wheels on it, each provided with thirty teeth. The digits from 0 to 9 are stamped three times around each recording wheel. The spring claws fit the gears of the first set of recording wheels. If a claw is pushed down, it engages the gear of a recording wheel, causing it to rotate. Studs on the wheel lead to carrying by engaging the next claw over. A second group of eight recording wheels, each wheel having thirty teeth, counts turns of the handle, recording the multiplier. These wheels are not shown on cuts of the machine shown at the Centennial.

A flat disk at the end of a lever on the left side serves as a brake on the operating wheels, indicating when the operating crank has been turned through one revolution.

A mark inscribed on the disc on the left side reads: PATENTED (/) JULY 16 1872 APRIL 29 1873 (/) GEO.B.GRANT. A mark inscribed on the top of that ring reads: 12 (/) 77

Compare MA.310645. It has longer cylinders and no mechanism for recording the multiplier. For a related, later U S. patent model, see MA.311940.


George B. Grant, “Improvement in Calculating Machines,” U.S. Patent 138245 (April 29, 1873).

George B. Grant, "Improvement in Calculating-Machine," U.S. Patent 129,335 (July 18, 1872).

George B. Grant, “On a New Difference Engine,” American Journal of Science, ser. 3, vol. 1 (August 1871), pp. 113–118.

George B. Grant, “A New Calculating Machine,” American Journal of Science, ser. 3, vol. 8 (1874), pp. 277–284.

L. Leland Locke, “George Barnard Grant,” Dictionary of American Biography, vol. 7, New York: Scribners, 1931, pp. 487–488.

Robert K. Otnes, “Calculators by George B. Grant,” Historische Buerowelt, no. 19, October 1987, pp. 15–17.

Accession files 118852 and 155183.

George B. Grant, “The Calculating Machine,” Boston: Albert J. Wright, Printer, 1878.

Date Made: ca 1877

Maker: Grant, George B.

Location: Currently not on view

Place Made: United States: Massachusetts, Boston

Subject: Mathematics


See more items in: Medicine and Science: Mathematics, Calculating Machines, Science & Mathematics


Exhibition Location:

Credit Line: Gift of Robert K. Otnes

Data Source: National Museum of American History

Id Number: 2016.0165.01Accession Number: 2016.0165Catalog Number: 2016.0165.01

Object Name: calculating machine

Physical Description: metal (mechanism material)wood (base material)Measurements: overall: 17.8 cm x 34.2 cm x 16.5 cm; 7 in x 13 15/32 in x 6 1/2 in


Record Id: nmah_1809267

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