Note:  Do not rely on this information. It is very old.

Calculating Machines

Calculating Machines are those designed to perform automatically certain mathematical processes such as addition, subtraction, multiplication, or division. The earliest known is that of Pascal, invented in 1642, and capable of performing addition and subtraction. Since that time many such machines have been designed, as a general rule cumbrous, complicated, and liable to derangement. Thomas's machine of 1850, modified in 1883 by Edmondson, gives very satisfactory results, performing multiplication and division of large numbers with great facility and accuracy by the mere turning of a handle. One turn of the handle when the instrument is arranged for the multiplication of a number, exposes that number to view, each digit on a small dial. A second turn exposes the number multiplied by 2, and so on for further turns. In fact, one turn is necessary for each unit in each digit of the multiplier: thus to multiply any number by 621, nine turns are necessary. For division, which process is simply the reverse of the additive process of multiplication, a turn of the handle is required for each unit in each digit of the quotient. It is equally easy to perform with decimals. The noise created by working the instrument is rather tiresome, but there is no doubt of its utility in many cases of tedious arithmetical calculation. Babbage's famous machine, the actual outcome of the theoretical design of which is now preserved in the South Kensington Museum, was intended to effect calculations of very great complexity, but failed.