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Sterling Currency Calculators
Sterling Addometer

Sterling currency Addometer.
Sterling currency Addometer.

Sterling currency Addometer.

296 x 50 x 15 mm (11.75" x 2.0" x 0.6").

1900s - 1960s.

For addition the stylus is placed in the hole against the appropriate large, inner number and dialed clockwise.
For subtraction the stylus is placed in the hole against the appropriate small outer number and dialed counter-clockwise.
Carry is automatic, and the instrument is cleared by pulling out the tab at bottom right.

As well as decimal models, versions were also made for working in Sterling currency, as above

In this version the wheel second from the right has numbers to 11 for dealing with pence. The wheel on the right deals with farthings (ie. 1/4 penny (name derived from fourthings)). The addometer shows the value £1,234 17s 11 3/4d.

Made by the Reliable Typewriter and Adding Machine Co., Chicago, Illinois, U.S.A.
Distributed in the UK. by Taylor's, 74 Chancery Lane, London.

Inside Addometer

Addometer with top cover removed.

This shows the number dials and between them, and slightly above, the plastic gears with strange teeth for transmitting carry overs.
The sliding metal strip at the bottom is for zeroing all the dials. Teeth can be seen sticking up from it.

The Addometer was very popular and they were produced for many years until cheap electronic calculators were available.

Vintage Calculators

© Text & photographs copyright Nigel Tout   2000-2017  except where noted otherwise.