Who Introduced The x Sign For Multiplication?

William Oughtred was born on 5 March 1574 in Eton, England died at 30 June 1660 (aged 86).

He was educated at Eton College and King's College at the University of Cambridge before entering service in the church.

Oughtred was the first mathematician to combine logarithmic scales to perform multiplication and division, developing the first slide rule in 1622.

He also introduced the "×" symbol for multiplication and the sin and cos abbreviations for the sine and cosine functions.

He invented the logaritmic slide rule by putting Lines of Numbers on top of each other.

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.

Books

He published, among other mathematical works, Clavis Mathematicae (The Key to Mathematics), in 1631. It became a classic, reprinted in several editions, and used by Wallis and Isaac Newton amongst others. It was not ambitious in scope, but an epitome aiming to represent current knowledge of algebra concisely. It argued for a less verbose style of mathematics, with a greater dependence on symbols; drawing on François Viète (though not explicitly),

Oughtred also innovated freely in symbols, introducing not only the multiplication sign as now used universally, but also the proportion sign (double colon ::). The book became popular around 15 years later, as mathematics took a greater role in higher education.

Other works were a treatise on navigation entitled Circles of Proportion, in 1632, and a book on trigonometry and dialling, and his Opuscula Mathematica, published posthumously in 1676. He invented a universal equinoctial ring dial of two rings.

• Clavis Mathematicae (1631) further Latin editions 1648, 1652, 1667, 1693; first English edition 1647.
  Circles of Proportion and the Horizontal Instrument (1632); this was edited by his pupil, William Forster.[24]
  Trigonometria with Canones sinuum (1657).

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.