Warren Experimental Calculating Machine Model

This is the second version of Warren’s calculating machine. Across the front is a brass rod with ten large teeth, one shorter one, and a hollow brass cylinder. Between the teeth are ten levers that link to toothed segments at the back of the machine. The front and back are open; the sides are of a ferrous metal painted black. At the top is a hollow brass rod, mounted across the machine, which has two brass circular structures on it. This is used as a plunger to activate the mechanism. Brass rods with large teeth extend from both sides of the back. There also is a ferrous piece in the shape of a large comb that is attached to the top back of the piece. The machine appears incomplete.
There are no maker’s marks.
Compare MA*311938 and MA*311939.
According to L. Leland Locke, Warren was a teacher, itinerant photographer and then watchmaker by trade. His invention was inspired by his reading about Charles Babbage’s difference engine in 1864. He designed his machines to demonstrate what might be done with machinery, not for sale. A more complete form of the machine, which was exhibited after Warren’s death, is now in the collections of the Michigan State University Museum.
L. Leland Locke, “The Warren Calculating Engine,” Business Equipment Topics, October, 1931, vol. 79, pp. 8, 9. 48, 49.
"Home and Foreign Gossip," Harper’s Weekly, May 22, 1875, vol. 19 #960, p. 423.
Currently not on view
Object Name
calculating machine
date made
Unlinked Name
Physical Description
ferrous metal (overall material)
brass (overall material)
overall: 18.2 cm x 66.3 cm x 30.2 cm; 7 5/32 in x 26 3/32 in x 11 7/8 in
place made
United States: Michigan, Three Oaks
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 L. Leland Locke

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