William Oughtred
More info
- Born
- 1574
- Died
- 1660
- Nationality
- English
- Known for
- The slide rule, the × sign
An English clergyman who set two logarithmic scales side by side and let them slide — inventing the slide rule around 1622.
Oughtred (1574–1660) was a country parson who taught mathematics for free to any student who sought him out, among them Christopher Wren and John Wallis. Around 1622 he took Gunter's logarithmic scale, laid two of them together and slid one past the other: the answer appeared without dividers. He built both a straight and a circular version — the first slide rules.
Slow to publish, he was beaten into print by a former pupil, Richard Delamain, who described a circular slide rule first, sparking a bitter priority dispute. Oughtred is also why we write multiplication as ×: he introduced the symbol in his 1631 Clavis Mathematicae. The slide rule he began remained the engineer's constant companion for 350 years.