The slide rule is a hand-held arithmetical instrument, formerly of
great practical importance.

Until the 20th-Century, the slide rule was one of only a handful of
machines with the capability of amplifying the power of the human mind.

Simple slide rules provide multiplication and division, typically to
3 or 4 significant decimal places, and possibly squaring and
square rooting.

More elaborate slide rules, such as the Post Versalog
( a sweet machine ) and various Keuffel & Esser
rules, are capable of a whole suite of "advanced" calculations,
using powers, exponents, roots, logarithms, trigonometric
functions, and inverses of those functions.

Sometimes, a slide rule was informally referred to as a "slip stick",
based on its shape, being much longer than wide, and on the sliding of
the scales past one another.

Circular slide rules providing basic functions were never common.

Cylindrical slide rules are capable of greater accuracy, but
uncommon.

Many variations on the slide rule were produced for various specialized
purposes, often having nothing to do with the arithmetical
operations.

Here are some misspellings :

"Sliderule", "slideruler" and "slide ruler".

2010 Mathematics Subject Classification : Primary 00A99

Secondary 26-01, 26A09

Walter Nissen 2013-03-30