Pro Calculo! Adder
date: label: date made
content: ca 1925
name: label: maker
content: Pittsburgh Typewriter and Supply Company
notes: label: Description
content: Adders like this one were designed to help consumers with addition, but did not actually add automatically. The surface of the metal instrument has seven slots that reveal part of seven flat notched metal bands below. To enter a digit, one pulls down a band with the metal stylus. The hooked shape of the slots exposed a notch in an adjacent band, making it possible to carry or to borrow digits. This adder also has a zeroing bar at the base. It fits into a dark brown paper case.
label: Description
content: Instruments of this type appeared as early as the 1600s, and sold commercially from the 1890s into the 1970s. They sold in Germany from the invention of the “Trick” in 1911. Otto Meuter patented a variation on this device that sold as the Arithma from 1920. Meuter received a fixed fee for each Arithma produced. With inflation, this sum soon was minute.
label: Description
content: Meuter decided to form another company with J. Bergmann and to market adders known as the Pro Calculo! and the Correntator. These sold widely in the 1920s. For example, the trade magazine Typewriter Topics reported that 15,000 ProCalculo! adders sold in 1926. In 1928, the product was renamed the Produx.
label: Description
content: References: <I>Typewriter Topics</I>, 59, February, 1925, p. 84. One model, offered by Pittsburgh Typewriter & Supply, sold for $3.00.
label: Description
content: <I>Typewriter Topics</I>, 67 (November, 1927), p. 50-51. New style adders introduced.
label: Description
content: Martin Reese, <I>Historische Buerowelt</I>, 43 (September 1995).
label: Location
content: Currently not on view
place: label: place made
content: United States: Pennsylvania, Pittsburgh
topic: label: Subject
content: Mathematics
setName: label: See more items in
content: Medicine and Science: Mathematics
label: See more items in
content: Adder
label: See more items in
content: Science & Mathematics
creditLine: label: Credit Line
content: Gift of L. Leland Locke
dataSource: label: Data Source
content: National Museum of American History
identifier: label: ID Number
content: MA.155183.26
label: catalog number
content: 155183.26
label: accession number
content: 155183
objectType: label: Object Name
content: adder
physicalDescription: label: Physical Description
content: paper (overall material)
label: Physical Description
content: metal (overall material)
label: Measurements
content: overall: 1 cm x 8.3 cm x 13 cm; 13/32 in x 3 9/32 in x 5 1/8 in