Dictionary of National Biography, 1885-1900/Forster, William (fl.1632)
FORSTER, WILLIAM (fl. 1632), mathematician, was a pupil of William Oughtred [q. v.], and afterwards taught mathematics 'at the Red bull over against St. Clements churchyard with out Temple bar.' While staying with Oughtred at Albury, Surrey, during the long vacation of 1630, the latter showed him a horizontal instrument for delineating dials upon any kind of plane, and for working most questions which could be performed by the globe. This invention Oughtred had contrived for his private use thirty years before. Forster persuaded him to make it public, and was ultimately allowed to translate and publish his master's treatise on the subject as 'The Circles of Proportion and the Horizontall Instrvment. Both invented, and the vses of both written in Latine by Mr. W[illiam] O[ughtred]. Translated into English and set forth for the publique benefit by William Forster,' 4to, London, 1632 (another edition, 1639), which he dedicated to Sir Kenelm Digby. A revised edition of this book was published by Arthur Haughton, another disciple of Oughtred, 8vo, Oxford, 1660. Forster had his name affixed to an 'Arithmetick, explaining the grounds and principles of that Art, both in whole numbers and fractions,' 12mo, London, 1673 (new edition, by Henry Coley, 12mo, London, 1686). The former edition is adorned by a supposed portrait of Forster, which is really that of John Weever, the antiquary.
[Ward's Lives of the Gresham Professors, i. 88; Chalmers's Biographical Dictionary, xxiii. 428; Granger's Biographical History of England (2nd edit), ii. 328.]