Calculating Machine Components

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These objects were collected by Brooklyn high school teacher and historian of mathematics L. Leland Locke. The metal shaft has six brass discs on it. A steel ring is between each of the discs. Each ring has four protrusions. Three are grouped together, and one is opposite the other three. The single protrusion is stamped with a number. Each disc has nine retractable pins. Rotating the rings sets the number of pins that protrude. Each disc also has two pins that protrude at all times. In addition to the six discs on the shaft, there are six other brass discs. Two of them have rings attached and pins. These rings are numbered 7 and 9. A ninth ring (without a disc) is numbered 8. The four brass discs without rings are numbered on the inside 8, 10, 11, and 12. Number 8 is cut to hold retractable pins, the other three discs are not. There are five miscellaneous smaller pieces.
Currently not on view
Physical Description
steel (overall material)
brass (overall material)
overall: 10 cm x 19.5 cm x 10 cm; 3 15/16 in x 7 11/16 in x 3 15/16 in
ID Number
nonaccession number
catalog number
Credit Line
Gift of L. Leland Locke
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Calculating Machines
Data Source
National Museum of American History


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