Curta Type I Calculating Machine

This compact cylindrical handheld calculating machine has black metal sides and a plastic top and operating handle. Eight slots along the side of the cylinder hold levers that are pulled down to set numbers. The digit entered appears at the top of the slot. Holes around the edge of the top reveal the digits of the multiplier, which may be up to six digits large. The result also shows through holes around the edge of the top, and may be 11 digits large. The top may be rotated, as one one would move a carriage on an earlier stepped drum calculating machine. Sliding decimal markers indicate decimal places in entries, multipliers, and results.
To zero the machine, one raises the carriage and rotates a black disc under the operating lever through one turn. The operating handle is pulled out for subtraction and division. Moving a lever on the side of the cylinder causes subtraction rather than addition in the revolution counting register. The machine fits in a black metal cylindrical case. The lid of the case turns clockwise to open.
The operating instructions received with the machine are stored separately.
The machine is marked on the case and on the side: CURTA. It is marked on the base: System Curt Herzstark (/) Made in Liechtenstein (/) by Contina AG Mauren (/) Type I No 34691. It is also marked there: Scholl (/) POSTSTRASSE 3. ZURICH. It is marked on the lid: OPEN.
This example of the Curta was used by Professor Charles T. G. Looney, who taught engineering at the University of Maryland.
The Curta calculating machine was invented by the Austrian Curt Hertzstark (1902–1988). He worked on the design during World War II as a prisoner at the Nazi concentration camp of Buchenwald, and produced the machine after the war in Leichtenstein. The Curta Type I was manufactured from 1949 until early 1972, when handheld electronic calculators replaced it.
Compare to 1981.0922.01.
Curt Hertstark, Interview with Erwin Tomash, September 10 and 11, 1987, Oral History 140, Charles Babbage Institute, Minneapolis, Minnesota.
Currently not on view
Object Name
calculating machine
date made
Contina AG Mauren
Physical Description
metal (overall material)
plastic (overall material)
overall: 12 cm x 5.7 cm x 5.7 cm; 4 23/32 in x 2 1/4 in x 2 1/4 in
place made
ID Number
catalog number
accession number
maker 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 Professor Charles T.G. Looney
Additional Media

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