Calculating Machines (1623–1674): Historically, humans have always used calculating aids when performing mathematical operations. The first of these devices that used moving parts was most likely the abacus. The modern version of this instrument is believed to have been invented by the Chinese in the 11th century and subsequently introduced into Europe. It consisted of a series of ceramic beads that the operator physically moved for calculations (see SLIDE RULE). There were a number of instruments designed during the 17th century that were designed to assist mathematical calculations. The Scottish mathematician John Napier (1550–1617), inventor of logarithms (see LOGARITHMS), promoted the use of Napier’s Bones around 1617. In the 1620s the Gunter’s scale was introduced by English mathematician Edmund Gunter (1581–1626), while the mechanical slide rule (see SLIDE RULE) was invented by the English mathematician William Oughtred (1574–1660). However, each of these devices simply aided calculations; they did not truly automate the calculation process. While there is no formal definition of what constitutes a calculating machine, it is often considered to be a device in which the operator enters information but does not physically perform the calculations. These instruments frequently rely on mechanical systems to perform the desired operation.
Credit for the invention of the first generation of automatic calculating machines is often given to the French mathematician Blaise Pascal. However, early in the 20th century evidence was discovered that placed first credit for the idea with the German scientist and mathematician William Schickard (1592–1635). In a series of letters to the German astronomer Johannes Kepler (1571–1630) around 1623,