Samuel Morland builds a mechanical calculator that will add and subtract
Sir Samuel Morland, 1st Baronet (1625 – 30 December 1695), or Moreland, was a notable English academic, diplomat, spy, inventor and mathematician of the 17th century, a polymath credited with early developments in relation to computing, hydraulics and steam power.
He invented a non-decimal adding machine (working with English pounds, shillings and pence)
The adding operation is performed by rotating the appropriate dials in the clockwise direction, pushing the stylus into the opening against appropriate number and turning the dial until the stylus will be stopped by the stop-pin. The subtraction can be done by rotating dials in the counterclockwise direction, pushing the stylus in the opening bellow the window, and rotating the dial until it moves bellow the appropriate number.
See http://history-computer.com/MechanicalCalculators/Pioneers/Morland.html for further details
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