A mechanical device consisting of a sliding portion and a fixed case, each marked with logarithmic axes. By lining up the ticks, it is possible to do Multiplication by taking advantage of the additive property of Logarithms. More complicated slide rules also allow the extraction of roots and computation of trigonometric functions. The development of the desk calculator (and subsequently pocket calculator) rendered slide rules largely obsolete beginning in the 1960s.

**References**

Electronic Teaching Laboratories. *Simplify Math: Learn to Use the Slide Rule.* New Augusta, IN: Editors and Engineers, 1966.

Saffold, R. *The Slide Rule.* Garden City, NY: Doubleday, 1962.

© 1996-9

1999-05-26