GEARS, WHEELS AND BUTTONS
The first mechanical calculator appeared in 1642, the creations of French intellectual and mathematics whizz kid Blaise Pascal as “a device that will eventually perform all four arithmetic operations without relying on human intelligence.”
Pascal's machine used geared wheels and could add and subtract two numbers directly and multiply and divide by repetition. Gottfried Leibniz then spent the best part of his life designing a four-operation mechanical calculator, based on his ingenious slotted ‘Leibniz wheel,’ but ultimately failing to produce a fully operational machine.
The Arithmometer
The Arithmometer: Soldiered on till 1915
That had to wait until 1820 and the patenting in France of Thomas de Colmar’s four function