William Oughtred and the Slide Rule

William Oughtred (1574–1660) invented the slide rule around 1622 — a mechanical calculator that used logarithms to reduce multiplication and division to the physical act of sliding two rulers against each other. The slide rule was the engineer's primary tool for 350 years, used to design the Golden Gate Bridge, the Saturn V rocket, and the first atomic bomb. Oughtred also introduced the × symbol for multiplication and the abbreviations sin and cos for trigonometric functions — notation used by every student today.