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2010/1/206 Mechanical addiator type calculator in case, with stylus and note paper (2), Arithma Adder, metal / leather / paper, made by Addiator Gesellschaft, Berlin, Germany, 1920-1930. Click to enlarge.

Arithma addiator calculator

Made 1920-1930
This object is part of a collection relating to the history and development of computing and other information technology assembled by Assoc Professor Allan Bromley of Sydney University, comprising calculators, mechanical and electronic analogue computers, computer components, kit computers, education computers, and associated ephemera.

Allan Bromley was a lecturer and researcher at the University of Sydney Basser Department of Computer Science from 1978 until his untimely death in August 2002. He specialised in Computer Architecture, Computer Logic and in particular the History of Computing. He was regarded as the world authority on Charles Babbage's Calculating Engines (instigating the rebuilt of DE2 at the Science Museum London) and the Ankithera Mechanism and had extensive knowledge on calculators, analogue computers, logic, stereopsis, totalisators, clocks and time keeping and mechanical engineering.


Object No.


Object Statement

Mechanical addiator type calculator in case, with stylus and note paper (2), Arithma Adder, metal / leather / paper, made by Addiator Gesellschaft, Berlin, Germany, 1920-1930

Physical Description

The Arithma mechanical addiator type calculator is a single sided device made from a gold plated aluminium, and can be used in both addition and subtraction. It features 10 vertical rows of gold and red teeth, with numerals 0:9, 0:1, 0:11, and 0:3/4, as well as ten windows above for viewing the numerals used in the mathematic equations. At the top of the device there is a brass bar, which can be pulled out to reset the windows to zero. 'ARITHMA' is overlayed at the top above the windows, along with symbol for pounds, shilling and pence.

The calculator is housed within a black leather, book style case with a pocket on the left for the calculator, a leather ring in the centre for holding the stylus and a set of eared corners for holding any scrap or calculating paper.

The stylus for the arithma is made from brass and features a flat top and pointed tip. The body of the stylus is decorated in a filed pattern for better grip.

Two sheets of calculating paper are also found inside the leather case. The first has a series of pencilled calculations, '4 5 6 / 3 9 / 2 7 / 4 1/2 / 4 16 3 1/2', while the second sheet is blank.



13 mm


101 mm










Credit Line

Donated through the Australian Government's Cultural Gifts Program in memory of Associate Professor Allan Bromley, 2010

Acquisition Date

20 January 2010

Cite this Object


Arithma addiator calculator 2019, Museum of Applied Arts & Sciences, accessed 28 May 2020, <>


{{cite web |url= |title=Arithma addiator calculator |author=Museum of Applied Arts & Sciences |access-date=28 May 2020 |publisher=Museum of Applied Arts & Sciences, Australia}}

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