Mechanical, electrically driven, stepped-gear calculator.
4 functions - addition, subtraction, automatic multiplication, automatic division.
The accumulator is at the top and can show a result to 20 places of decimals. The numbers entered can be to 10 places of decimals.
375 mm x 320 mm x 215 mm (15" x 13" x 9"), 16 Kg (35 lbs).
Made in Switzerland by H.W. Egli S.A., Zurich.
Dates from mid-1950s (serial number 75173).
View underneath, with the bottom cover removed, showing the electric motor which powers this model. Hand-operated models were also available.
The name "Madas" is derived from the initial letters of "Multiplication, Automatic Division, Addition, & Subtraction". It is a mechanical calculator, driven by an electric motor and automatically performs the four standard functions (with a lot of whirring and clunking !).
These machines evolved over many years from the "Millionaire" calculator.
Gerald Saudan has a site with information about everything that you would want to know about Madas mechanical calculators at http://www.madas.ch/, including details of all of the models.
Also, the history and internal workings of Madas calculators are described in an article by Ray Mackay at http://www.xnumber.com/xnumber/madas.htm.
In John Wolf's Web Museum there is an overview of Millionaire and Madas calculators, including pages showing a Madas calculator disassembled into its various mechanisms. It vividly illustrates the vast number of high-precision components required and the ingenuity in squeezing everything into a small space.
© Text & photographs copyright Nigel Tout 2000-2018 except where noted otherwise.