William Forster (mathematician)


William Forster was an English mathematician, known for publishing a book describing inventions of William Oughtred.

Life and publications

Little is known of Forster's life. He was a student of William Oughtred; while staying with Oughtred at Albury, Surrey, during the long vacation of 1630, the latter showed him two instruments: a circular slide rule, and a "horizontal instrument" for delineating sundials upon any kind of plane and for demonstrating astronomical principles. Oughtred had written instructions for these in Latin. Forster persuaded him to make them public, and was ultimately allowed to translate and publish Oughtred's treatise as The Circles of Proportion and the Horizontall Instrvment. Both invented, and the vses of both written in Latine by Mr. W O. Translated into English and set forth for the publique benefit by William Forster. It was dedicated to Sir Kenelm Digby.
The book includes Forster's address: "at the Red bull over against St. Clements churchyard with out Temple bar"; it is thought he taught mathematics there.
Forster's preface suggested that another person had claimed invention of the instruments; this led to a dispute involving him, Oughtred and Richard Delamaine, a student of Oughtred.
In 1667 he published Forster's Arithmetick, intended for merchants and accountants. It was republished in 1673, and a new edition by Henry Coley appeared in 1686; this suggests that Forster died between the publication of the second and third editions.