Grant Experimental Model Calculating Machine

This lever-set non-printing connection pawl calculating machine is the last experimental model of George B. Grant, designed to incorporate subtraction and division as well as addition and multiplication. It has a wooden base and a brass frame. Five pins slide to set numbers. Positions next to the pins are labeled from 0 to 9. Moving back a pin drives back a toothed rack.
Behind the racks is a movable carriage with 11 gears on it. The carriage can be set at six different positions. When the racks are pushed back (there is no cam to drive the racks), the gears are engaged, and rotate in proportion to the number set. The gears move in the opposite direction when the racks are moved forward. Carry teeth are arranged in a spiral shaft above the carriage. A lever at the front of the machine may be rotated in a way that may affect the action of the carry shaft. A crank on the right zeros the result shaft.
This model represents Grant’s enduring interest in the improvement of calculating devices. It did not lead directly to any commercial product.
Currently not on view
Object Name
calculating machine
date made
after 1895
Grant, George B.
Physical Description
brass (overall material)
wood (overall material)
overall: 21.2 cm x 23.5 cm x 30 cm; 8 11/32 in x 9 1/4 in x 11 13/16 in
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

Visitor Comments

Add a comment about this object

**Please read before submitting the form**

Have a comment or question about this object to share with the community? Please use the form below. Approved comments will appear on this page and may receive a museum response (but we can't promise). Please note that we generally cannot answer questions about your own artifacts or comment on their value, rarity, or collectibility.

Have a question about anything else, or would you prefer a personal response? Please visit our FAQ or contact page.

Personal information will not be shared or result in unsolicited e-mail. See our privacy policy.

Enter the characters shown in the image.