Engineer's slide rule, c 1800. This boxwood slide rule shows the logarithmic scale and was made by W & S Jones. The most important development of the 18th century was the Soho slide rule, named after the district of Birmingham surrounding the Boulton and Watt factory. The rapid increase in the use of powered machinery at the end of the 18th century created the need for a new type of slide rule. Made to a high standard of accuracy, the Soho slide rule was able to deal with the complex calculations to do with the design and operation of machines and engines.
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