Slideshow: Slide rules and charts - a personal collection

Mort Hans -September 21, 2012

Introduction (by Steve Taranovich, EDN senior technical editor)

The slide rule
The slide rule, sometimes called a slipstick, was a type of mechanical analog computer. It was and still is, used primarily for multiplication and division, and also for functions such as roots, logarithms and trigonometry. They come in a diverse range of styles and generally appear in a linear or circular form with a standardized set of markings (scales) essential to performing mathematical computations. Slide rules manufactured for specialized fields such as aviation or commerce typically feature additional scales that aid in calculations common to that field.

William Oughtred and others developed the slide rule in the 17th century based on the emerging work on logarithms by John Napier.

Slide rules were key to engineers in the 1950s and 1960s even though digital computing devices were being slowly introduced, but engineering students like myself from 1968-1972 could not afford the electronic versions.

Somewhere around 1974 the electronic scientific calculator took over the market and made slide rules virtually obsolete for the most part except for some "die-hard" traditionalists engineers who kept the slide rule in its case hanging from their belt.

The slide chart
A slide chart is a hand-held device, usually of paper, cardboard, or plastic, for conducting simple calculations or looking up information.

A circular slide chart is sometimes referred to as a wheel chart or Volvelle (Courtesy of Wikipedia: Led Zeppelin used a Volvelle on their "Led Zeppelin III" album. The cover and interior gatefold art consisted of a surreal collection of seemingly random images on a white background, many of them connected thematically with flight or aviation (as in "Zeppelin"). Behind the front cover was a rotatable laminated card disc, or volvelles, covered with more images, including photos of the band members, which showed through holes in the cover. Moving an image into place behind one hole would usually bring one or two others into place behind other holes.)

Slide charts are common collectables among technical people. Here is Mort Hans' presentation:

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