The
1600's
1612: John Napier made the first printed use of the
decimal point.
1622: William Oughtred created the slide rule
(originally circular) based on Napier's logarithms that was to be the primary
calculator of engineers through the 19th and early 20th centuries.
(The picture here is of an 1880's cylindrical Slide Rule, effectively 200
inches long, and capable of four digit accuracy).
1623: William Schickard described a machine that combined the concept
of Napier's bones (in a cylindrical form) with a simple adder that allowed
the user to more easily complete the multiplication of multi-digit numbers.
1642: Blaise Pascal created an adding machine with automatic carries
from one position to the next. The son of a merchant, Pascal devised a
machine that contained several dials that could be turned with the aid
of a stylus. Addition was achieved by the underlying gears turning as each
digit was dialled in, the cumulative total being displayed in a window
above the "keyboard". While several models were completed, Pascal's machine
(often called the "Pascalene") was more likely to be found in the living
rooms of their owners as a conversation piece rather than in the work room.
1673: Using a stepped cylindrical gear, Gottfried Leibniz built a calculator
capable of multiplication in which a number was repeatedly, and automatically
added into an accumulator.