Simplex Calculating Machine

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This key-set, non-printing stepped drum calculating machine has a metal case painted black. Each of the nine columns of keys has nine black plastic keys. Between each row of keys, rods that are black on one side and white on the other serve as decimal markers. The crank for operating the machine angles out of the right side, at the front. A lever near it is marked Repeat in one position and Release in the other. In the front on the left is a lever that may be intended for shifting the carriage. Above the keyboard is a row of nine windows. This indicates a number set on the keys. On the left side is a lever. It is marked Subt.& Div. in one position and Add.& Mult. in the other.
In back of the keyboard is a carriage with two rows of windows. The front row holds nine digits, and the back row, 16. On the right side of the carriage, a zeroing knob ia next to each row of windows. The machine has four rubber feet.
A mark on the left front reads: Simplex. A mark under the carriage on the left side reads: 2741. A paper tag hanging from the object reads: 28.
This machine closely resembles a Record calculating machine. Compare to MA.311949. It is number 28 in the collection of Felt & Tarrant Manufacturing Company.
E. Martin, The Calculating Machines (Die Rechenmaschinen), trans. P. A. Kidwell and M. R. Williams, Cambridge: MIT Press, 1992, pp. 274–276.
Currently not on view
date made
ca 1925
place made
Deutschland: Berlin, Berlin
Physical Description
brass (overall material)
plastic (overall material)
steel (overall material)
overall: 19.7 cm x 45 cm x 35 cm; 7 3/4 in x 17 23/32 in x 13 25/32 in
ID Number
accession number
catalog number
Credit Line
Gift of Victor Comptometer Corporation
See more items in
Medicine and Science: Mathematics
Science & Mathematics
Calculating Machines
Data Source
National Museum of American History