Dictionary of National Biography, 1885-1900/Foster, Samuel
FOSTER, SAMUEL (d. 1652), mathematician, a native of Northamptonshire, was admitted a sizar at Emmanuel College, Cambridge, 23 April 1616, as a member of which he proceeded B.A. in 1619, and M.A. in 1623. Upon the death of Henry Gellibrand, professor of astronomy at Gresham College, he was elected to the post 2 March 1636, but resigned on the following 25 Nov., being succeeded by Mungo Murray. In 1641, Murray having vacated the professorship by his marriage, Foster was re-elected on 26 May. During the civil war and Commonwealth he was one of the society of gentlemen who met in London for cultivating the 'new philosophy,' from which eventually arose the Royal Society. In 1646 Wallis received from Foster a theorem 'De triangulo sphaerico,' which he afterwards published in his 'Mechanica,' fol. edit. cap. v. prop. 24, p. 869. Foster died at Gresham College in May (not in July, as Ward has it) 1652, and was buried in the church of St. Peter the Poor in Broad Street. From his will (P. C. C. 111, Bowyer), dated 7, and proved 18, May 1652, he seems to have been a zealous nonconformist. Dr. John Twysden gives him the character of 'a learned, industrious, and most skilful mathematician' (Preface to Foster's Miscellanies), 'the truth of which,' adds John Ward, 'he has abundantly shewn by his works. Nor did he only excell in his own faculty, but was likewise well versed in the antient languages; as appears by his revising and correcting the "Lemmata" of Archimedes, which had been translated into Latin from an Arabic manuscript, but not published, by Mr. John Greaves' (Smith, Vita J. Gravii, p. 28). He made several curious observations of eclipses, both of the sun and moon, as well at Gresham College as in other distant places (Miscellanies). And he was particularly famous for inventing and improving many planetary instruments (Sherburn, Appendix to Manilius, p. 97). He published little himself, but many treatises written by him were printed after his death (Ward, Lives of Gresham Professors, i. 86), though John Twysden and Edmund Wingate, his editors, state his long infirmities caused them to be left very imperfect (Preface to Foster's Four Treatises of Dialling), and Twysden complains that some people had taken advantage of his liberality by publishing his works as their own (Preface to Foster's Miscellanies). In the following list of his works the first two only were published by himself: 1. 'The Use of the Quadrant,' 4to, London, 1624. An octavo edition was published soon after the author's death in 1652 by A. Thompson, who says in his preface that the additional lines were invented, and the uses written, for an 'appendix' to Gunter's 'Quadrant;' only some few copies were printed alone for the satisfaction of Foster's friends. Other editions appear among Gunter's 'Works,' 4to, 1653, 1662, and 1673. 2. 'The Art of Dialling; by a new, easie, and most speedy way,' 4to, London, 1638. An edition published in 1675, 4to, has several additions and variations taken from the author's own manuscript; as also a 'Supplement' by the editor, William Leybourn. John Collins also published in 1659 'Geometrical Dyalling, being a full explication of divers difficulties in the works of learned Mr. Samuel Foster,' 4to. 3. 'Posthuma Forsteri, the description of a ruler, upon which is inscribed divers scales and the uses thereof. Invented and written by Mr. Samuel Forster' [edited by Edmund Wingate], 4to, London, 1652. 4. 'Elliptical or Azimuthal Horologiography, comprehending severall wayes of describing dials upon all kindes of superficies, either plain or curved; and unto upright stiles in whatsoever position they shall be placed. Invented and demonstrated by Samuel Foster' [edited by John Twysden and Edmund Wingate], 4 pts. 4to, London, 1654. 5. 'Miscellanea: siue lucubrationes mathematics. Miscellanies: or Mathematical lucubrations of Mr. Samuel Foster, published, and many of them translated into English, by ... John Twysden. . . . Whereunto he hath annexed some things of his own. (Epitome Aristarchi Samii de magnitudinibus et distantiis . . . solis, lunae, et terrae. Lemmata Archimedis ... e ... codice MS. Arabico a Johanne Gravio traducta. A short treatise of fortifications, by J. T. [i.e. J. Twysden?]. Extract of a letter [on dialling] by Im. Halton. Aequations arising from a quantity divided into two unequal parts: and the second book of Euclides Elements, demonstrated by species by John Leeke).' Latin and English, 19 pts. fol. London, 1659. 6. 'The Sector altered, and other scales added, with the description and use thereof,' an improvement of Gunter's sector, and printed in the fourth and fifth editions of his 'Works,' 4to, 1662 and 1673, by William Leybourn, who in the latter edition corrected some mistakes which had appeared in the former from Foster's own manuscript. 7. 'The Description and Use of the Nocturnal; with the Addition of a Ruler, shewing the Measures of Inches and other Parts of most Countries, compared with our English ones,' 4to [London? 1685?]. Foster left numerous manuscript treatises in addition to those printed by his friends. Of these two were in the possession of William Jones, F.R.S., in the middle of the last century: 1. 'The Uses of a General Quadrant,' fol. 2. 'Select Uses of the Quadrant,' 8vo, dated 1649.
[Ward's Lives of the Gresham Professors, with manuscript notes by the author, in Brit. Mus. i. 85-7; Brit. Mus. Cat., under 'Forster' and 'Foster;' Wood's Athenae Oxon. (Bliss), ii. 405406, iii. 327.]