(Text reads “The Adder” “Registered Trade Mark”)
The Adder was a 3 digit adding machine which added one digit at a time via a ten key keyboard. It was designed by Arthur James Postans (1867–1940), a British engineer from South Kensington, London, England. He applied for a British Patent (along with patents in a number of other countries) in 1904 and later received patents for similar machines in Sweden, Switzerland and Canada as well as improved designs in the UK.1 According to Martin, the production of The Adder began in 1908 and ended in the 1920s.2
As with the other adders in this collection, the adding was done primarily to the right hand column, but in this case with the elaborated possibility also of adding 10. (To add 30 the 10 key would be depressed three times). On the left is a clearing lever which resets the machine to zero in all three windows.
Provenance: ex “Dunottar Collection” of the late David Gamble, 2014.
Patents
The UK Patent for The Adder was granted to Arthur J. Postans as inventor on 1 December 1904 - see UK Patent Application GBD190224868.
The US Patent for The Adder was granted to Arthur J. Postans as inventor on 11 April 1905 - see US Patent 786839.
Instruction brochure.
The instruction brochure for The Adder is shown below:
1 The Adder, http://history-computer.com/CalculatingTools/Gadgets/Adder.html, viewed 26 May 2014 (↑)
2 Ernest Martin, The Calculating Machines (a translated reprint of Die Rechenmaschinen, 1925), The MIT Press Cambridge, Massachusetts London, England, and Tomash Publishers Los Angeles and San Francisco, 199, p. 200. (↑)
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