Hand calculator with paper counting rods, Kangxi period (1662—1722). Brass, paper rolls and iron in wooden case, paper and iron. 5×19 x 11.5 cm. The Palace Museum, Beijing.
Hand Calculator with Paper Counting Rods
Counting rods and the abacus have been the main mechanical calculating aids available to Chinese mathematicians since ancient times. In Europe in the early 1600s, a Scottish mathematician named John Napier invented a method of performing arithmetical operations by manipulating rods printed with numbers. The rods were often made of bone. His technique essentially reduced complicated multiplication and division problems to addition and subtraction. The introduction of numbers onto counting rods in China, based on ‘Napier’s Bones’, followed soon afterwards and for some time seem to have been in fairly wide use. This particular calculator has ten copper rods, each with a six-toothed gear, two middle ones in between the two on the top, and two on the bottom, so that pairs of rods can move in conjunction. Not only can this machine perform multiplication and division but it can also calculate squares, cubes, square roots and cubic roots.
