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slide rule

noun
1.
a device for performing mathematical calculations, consisting essentially of a ruler having a sliding piece moving along it, both marked with graduated, usually logarithmic, scales: now largely replaced by the electronic calculator.
Origin
1655-1665
1655-65 for earlier sense; 1875-80 for current sense
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Based on the Random House Dictionary, © Random House, Inc. 2014.
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British Dictionary definitions for slide-rule

slide rule

noun (obsolete)
1.
a mechanical calculating device consisting of two strips, one sliding along a central groove in the other, each strip graduated in two or more logarithmic scales of numbers, trigonometric functions, etc. It employs the same principles as logarithm tables
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition
© William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins
Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
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Word Origin and History for slide-rule
n.

also slide rule, mathematical calculating tool, 1838, from slide (v.) + rule (n.). So called for its method of operation. Earlier sliding-rule (1660s).

Online Etymology Dictionary, © 2010 Douglas Harper
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Encyclopedia Article for slide-rule

slide rule

a device consisting of graduated scales capable of relative movement, by means of which simple calculations may be carried out mechanically. Typical slide rules contain scales for multiplying, dividing, and extracting square roots, and some also contain scales for calculating trigonometric functions and logarithms. The slide rule remained an essential tool in science and engineering and was widely used in business and industry until it was superseded by the portable electronic calculator late in the 20th century.

Learn more about slide rule with a free trial on Britannica.com
Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.
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