by Ruth Wallis
© Oxford University Press 2004 All rights reserved
Kersey, John, the elder (bap. 1616, d. 1677), mathematician, son of Anthony Carsaye or Kersey and Alice Fenimore, was baptized at Bodicote, near Banbury, Oxfordshire, on 23 November 1616. He was employed, probably in the 1630s, as tutor to Alexander and Edmund Denton, grandsons of the royalist Sir Alexander Denton, kt (1596-1645) of Hillesden House, Buckinghamshire. In the 1673 dedication of his Elements of ... Algebra to his former pupils, Kersey expressed gratitude to the family which 'gave both birth and nourishment to his mathematical studies'; his reference to Charles I as 'of ever-blessed memory' might or might not have been from conviction.
By 1650 Kersey was established in London, in Charles Street, near the Covent Garden piazza, as teacher of mathematics and surveyor, and had made the acquaintance of Edmund Wingate, author of Natural and Artificiall Arithmetique (2 vols., 1630). Wingate's stock of his Arithmetique was becoming exhausted, and he had sufficient confidence in Kersey's ability to ask him to revise and augment the first part of this work for reprinting as a self-contained volume. In this second edition of over 480 pages, published as Arithmetique Made Easie (1650), Kersey added a seven-chapter appendix. He 'framed totally anew, the Rules of Division, Reduction ... delivered the Doctrine of Fractions ... newly framed the Extraction of ... roots'. There were eleven further editions by the end of the century, and from 1704 the work was edited by George Shelley (1666-1736) and continued to appear until 1760.
This success encouraged Kersey to embark on his major work, the two-volume Elements of that Mathematical Art Commonly called Algebra (1673-4). It was ready in 1667, and his friend John Collins (1626-1683) made strenuous efforts to persuade booksellers to undertake the printing, but times were hard and paper dear. A prospectus was issued early in 1672. In the May Isaac Newton (1642-1727) promised to subscribe, and by July had procured three other subscriptions from Cambridge. Richard Towneley (1629-1707) of Towneley, near Burnley, Lancashire, likewise subscribed and canvassed support.
Kersey based his work mainly on English authors, including Harriot, Oughtred, John Wallis, and Isaac Barrow. Since the subject had only recently attracted attention, his list of all signs and abbreviations is especially interesting. Negative numbers he regarded as fictitious. By 1676 Collins reported that sales were good, and the book became a standard authority used by later authors, such as Edward Cocker. According to one writer, it was judged 'to be the clearest, and most comprehensive system ... in any language' (Granger, 2.363-4).
Kersey had been living at the sign of The Globe, Shandoise (Chandos) Street, off St Martin's Lane, Covent Garden, since at least 1670. He died there in mid-May 1677, having long suffered from a stone in the bladder, and was buried at St Paul, Covent Garden, on 23 May. Another John Kersey, presumably his son although nothing is known of a marriage, was a teacher of mathematics in Chandos Street in 1697 and probably died about 1698. The Wingate series had no reference to Kersey the elder's 1677 death, but in 1699 new publishers described the author as 'late teacher of the Mathematicks'; possibly confused themselves, they confused posterity as well.
John Kersey the younger (b. c.1660, d. in or after 1721), lexicographer, was born about 1660, the son of John, citizen and stationer of St Paul's, Covent Garden, London, who was probably the second John Kersey aforesaid. This third man of the same name was apprenticed in the Stationers' Company on 6 October 1673 to John Martyn and freed on 11 October 1680. In the fourteenth edition (1720) of Wingate's Arithmetique there appeared the claim that it was 'now exactly corrected by John Kersey, the last author's son', and the Dictionary of National Biography, following this source, also made Kersey the younger a son of Kersey the elder.
Kersey the younger was in a publishing partnership with Henry Faithorne at The Rose in St Paul's Churchyard in 1681-6. Their Weekly Memorials for the Ingenious, an abstracting journal, appeared for a year from January 1682; after a quarrel with the anonymous editor, Kersey may have edited the latter issues. He was probably the translator of Plutarch's Discourse to an Unlearned Prince (1685), reprinted in 1870 in Plutarch's Morals, vol. 4. In 1687 he took as apprentice his brother Alexander, who may have died before completing. He called himself 'Philobibl.' when revising and augmenting the folio sixth edition of E. Phillips's New World of Words, or, Universal English Dictionary (1706; 3rd edn, 1721); he had added '20,000 hard words in arts and sciences', while stating that it was 'no part of our design to teach liberal or mechanical arts and sciences as a late learned author has attempted to do', referring to the 1704 Lexicon technicum by John Harris. In 1708 he published the octavo Dictionarium Anglo-Britannicum, a condensed 'portable' version of the 'voluminous' 1706 work. He was ostensibly still alive when a third, corrected and enlarged, edition appeared in 1721.
RUTH WALLIS
Sources
S. P. Rigaud and S. J. Rigaud, eds., Correspondence of scientific men of the seventeenth century, 2 vols. (1841)
E. G. R. Taylor, The mathematical practitioners of Tudor and Stuart England (1954), 219
DNB
J. Granger, A biographical history of England, from Egbert the Great to the revolution, 2 (1769), 363-4
D. F. McKenzie, ed., Stationers' Company apprentices, [2]: 1641-1700 (1974), nos. 2496, 2903
H. R. Plomer and others, A dictionary of the printers and booksellers who were at work in England, Scotland, and Ireland from 1668 to 1725 (1922), 114-15, 178
Likenesses
W. Faithorne, line engraving (after a painting by Soust, 1672), BM, NPG; repro. in J. Kersey, Elements of ... algebra (1673), frontispiece
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