SLIDE RULE

The slide rule (often nicknamed a "slipstick") is a mechanical analog computer, consisting of calibrated strips, usually a fixed outer pair and a movable inner one, with a sliding window called the cursor. It was the most commonly used calculation tool in science and engineering. Their use began to wane as computers were introduced, starting in the 1950s, and the scientific calculator made them largely obsolete by the early 1970s. Despite their similar appearance, a slide rule serves a purpose different from that of a standard ruler: a ruler measures physical distances and aids in drawing straight lines, while a slide rule performs mathematical operations.