Easy…and Accurate: Mechanical Calculators
Easy...and Accurate: Mechanical Calculators
For some calculations, the slide rule’s flexibility and simplicity outweighed its imprecision. But many tasks, such as accounting or taking inventory, demand the exact results that come from counting instead of measuring. Mechanical calculators do that.
Solutions ranged widely, from “Napier’s Bones” in 1617, which used a sequence of sticks for multiplication, to the extremely elegant Curta calculator of the 1940s.
The original idea for this multiplication aid probably came from the Middle East. Europeans learned it from John Napier’s Rabdologia in 1617.
Users arranged rows of “bones” (bars inscribed with number sequences), then added certain numbers on the bars to do multiplication.