who invented the first gear driven calculating machine
Mechanical calculator Surviving notes from Wilhelm Schickard in 1623 reveal that he designed and had built the earliest of the modern attempts at mechanizing calculation. His machine was composed of two sets of technologies: first an abacus made of Napier's bones, to simplify multiplications and divisions first described six years earlier in 1617, and for the mechanical part, it had a dialed pedometer to perform additions and subtractions. A study of the surviving notes shows a machine that would have jammed after a few entries on the same dial,[1] and that it could be damaged if a carry had to be propagated over a few digits (like adding 1 to 999).[2] Schickard abandoned his project in 1624 and never mentioned it again until his death eleven years later in 1635.