The Rev. William Oughtred (5 March 1574 – 30 June 1660) was an English mathematician and Anglican minister.
After John Napier invented logarithms, and Edmund Gunter created the logarithmic scales (lines, or rules) upon which slide rules are based, it was Oughtred who first used two such scales sliding by one another to perform direct multiplication and division; and he is credited as the inventor of the slide rule in 1622. Oughtred also introduced the "×" symbol for multiplication as well as the abbreviations "sin" and "cos" for the sine and cosine functions.
Oughtred was born at Eton in Buckinghamshire (now part of Berkshire), and educated there and at King's College, Cambridge, of which he became fellow.Being admitted to holy orders, he left the University of Cambridge about 1603, for a living at Shalford; he was presented in 1610 to the rectory of Albury, near Guildford in Surrey, where he settled. He married Christsgift Caryll, (niece) of the Caryll family of Tangley Hall at Wonersh,of which Lady Elizabeth Aungier (daughter of Sir Francis), wife of Simon Caryll 1607-1619, was matriarch and then dowager until her death c.1650.
About 1628 he was appointed by the Earl of Arundel to instruct his son in mathematics.He corresponded with some of the most eminent scholars of his time, including William Alabaster, Sir Charles Cavendish, and William Gascoigne.He kept up regular contacts with Gresham College, where he knew Henry Briggs and Gunter.
He offered free mathematical tuition to pupils, who included Richard Delamain, and Jonas Moore, making him an influential teacher of a generation of mathematicians. Seth Ward resided with Oughtred for six months to learn contemporary mathematics, and the physician Charles Scarburgh also stayed at Albury; John Wallis, and Christopher Wren corresponded with him.Another Albury pupil was Robert Wood, who helped him get the Clavis through the press.
The invention of the slide rule involved Oughtred in a priority dispute with Delamain. They also disagreed on pedagogy in mathematics, with Oughtred arguing that theory should precede practice.
He remained rector until his death in 1660 at Albury, a month after the restoration of Charles II.
Interest in the occult
Oughtred had an interest in alchemy and astrology.The testimony for his occult activities is quite slender, but there has been an accretion to his reputation based on his contemporaries.
According to John Aubrey, he was not entirely sceptical about astrology. William Lilly, an eminent astrologer, claimed in his autobiography to have intervened on behalf of Oughtred to prevent his ejection by Parliament in 1646.In fact Oughtred was protected at this time by Bulstrode Whitelocke.Aubrey states that (despite their political differences) he was also defended by Sir Richard Onslow.
Elias Ashmole was (according to Aubrey) a neighbour in Surrey, though Ashmole's estates acquired by marriage were over the county line in Berkshire; and Oughtred's name has been mentioned in purported histories of early freemasonry, a suggestion that Oughtred was present at Ashmole's 1646 initiation going back to Thomas De Quincey.It was used by George Wharton in publishing The Cabal of the Twelve Houses astrological by Morinus (Jean-Baptiste Morin) in 1659.
He expressed millenarian views to John Evelyn, as recorded in Evelyn's Diary, entry for 28 August 1655.