英和和英

出典:『Wikipedia』 (2011/06/08 05:10 UTC 版)

英語による解説

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A Pinwheel calculator was a class of mechanical calculator popular in the 19th and 20th century using, for its calculating engine, a set of wheels that had an adjustable number of teeth. These wheels, also called pinwheels, could be set by using a side lever which could expose anywhere from 0 to 9 teeth, and therefore when coupled to a counter they could, at each rotation, add a number from 0 to 9 to the result. By linking these wheels with carry mechanisms a new kind of calculator engine was invented. Turn the wheels one way and one performs an addition, the other way a subtraction. As part of a redesign of the arithmometer, they reduced the cost and the size of a mechanical calculators on which one could easily do the four basic operations (add, subtract, multiply and divide) by an order of magnitude.