Grant Calculating Machine, Centennial Model

In 1876 the Massachusetts inventor and entrepreneur George B. Grant displayed this calculating machine, 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 20 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 18 positions on the cylinder with a locking pin. This collar supports 18 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 20 recording wheels on it, each provided with 30 teeth. The digits from 0 to 9 are stamped three times around each wheel. The spring claws fit the gears of the recording wheels. If a claw is pushed down, it engages the gear of the recording wheel, causing it to rotate. Studs on the wheel lead to carrying by engaging the next claw over.
This model has no mechanism for displaying the multiplier or multiplicand. 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.
For a related, later U S. patent model, see MA*311940.
The judges at the Centennial Exhibition gave Grant an award for his invention, and described his machine as “superior to all other instruments of its class yet produced.” It was lauded by actuaries and distinguished professors, but never gained large sales. This version of the machine sold for $100.
George B. Grant, “Improvement in Calculating Machines,” U.S. Patent 138245 (April 29, 1873).
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.
Currently not on view
Object Name
calculating machine
date made
Grant, George B.
Physical Description
brass (overall material)
wood (overall material)
steel (overall material)
overall: 18.6 cm x 46.3 cm x 15 cm; 7 5/16 in x 18 7/32 in x 5 29/32 in
place made
United States: Massachusetts, Boston
ID Number
catalog number
accession number
Science & Mathematics
Calculating Machines
See more items in
Medicine and Science: Mathematics
Calculating Machines
Data Source
National Museum of American History, Kenneth E. Behring Center
Credit Line
Gift of Edwin A. Bayley
Additional Media

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