Kersey, John (DNB00)
KERSEY, JOHN, the elder (1616–1690?), mathematician, son of Anthony Carsaye or Kersey and Alice Fenimore, was baptised at Bodicote, near Banbury, Oxfordshire, on 23 Nov. 1616 (cf. Hearne, Coll., ed. Doble. I Oxf. Hist. Soc.,ii. 11). Kersey early came to London, where he seems to have had relatives (cf. Robinson, Reg. Merchant Taylors' School, i. 104; Chester, London Marriage Licenses, p. 790), and gained a livelihood as a teacher. At first (1650) he lived at the corner house (opposite to the White Lion) in Charles Street, near the piazza in Covent Garden, but afterwards moved to Chandos Street, St. Martin's Lane. He was acquainted with John Collins [q. v.], the 'attorney-general for the mathematics,' who persuaded him to write his work on algebra. He was a friend of Edmund Wingate [q. v.], and edited the second edition of his 'Arithmetic' in 1650, and subsequent issues till 1683. Kersey obtained a wide reputation as a teacher of mathematics. At one time he was tutor to the sons of Sir Alexander Denton of Hillesden House, Buckinghamshire, 'whose family,' he writes, 'gave both birth and nourishment to his mathematical studies' (Elements, Ded.; Hearne, Coll. ii. 11). To his pupils Alexander and Edmund Denton he dedicated his first and principal original work, 'The Elements of Mathematical Art, commonly called Algebra,' in two folio volumes, dated respectively 1673 and 1674. A portrait of the author, by Faithorne, was prefixed to the first volume. Both Wallis and Collins wrote in 1672 in the highest terms of their anticipations of this work (cf. Corresp. of Scientific Men, ii. 554; and Nichols, Lit. Illustrations, iv. 46), and on its publication it became a standard authority. It was honourably mentioned in the 'Philosophical Transactions' (viii. 6073-4), and was commended by Hutton. Kersey's method of algebra was employed in Cocker's 'Arithmetic' of 1703. Kersey is said (Beesley, Hist. of Banbury, p. 485) to have died about 1677, but the date must he later, as the eighth edition of Wingate was edited by him in 1683. In the tenth, published in 1699, he is spoken of as 'late teacher of the Mathematicks.'
John Kersey the younger (fl. 1720), lexicographer, son of John Kersey the elder, with whom he has been much confused, revised the work of his father in the fourteenth edition of Wingate (1720), and he, more probably than his father, contributed the 'Discourse to an unlearned Prince' to the 'Translation of Plutarch's Morals,' which appeared 1684-5 (republished 1870). He was mainly occupied with lexicography. The sixth edition of Phillips's 'New World of Words,' which was published in 1706, was edited by him (Pref. to Dict. Anglo-Britannicum, 1 708). He greatly added to the number of words (cf. H. B. Wheatley, 'Chronological Notice of the Dictionaries of the English Language,' in Proc. Phil. Soc. 1866), and published a seventh edition in 1720. Another dictionary, the 'New English Dictionary,' of which the first edition is said to have appeared in 1702 (2nd 1713, 3rd 1731, &c.), was also assigned on the title-page to J. K., but Kersey's responsibility for the work has been questioned. In 1708 was printed his 'Dictionarium Anglo-Britannicum, comprehending a brief explication of all sorts of difficult words;' a new edition in 1715 contained 'words and phrases made use of in our ancient statutes, old records, charters;' the third edition appeared in 1721. The date of his death is uncertain. From Kersey's 'Dictionarium' Chatterton borrowed part of his archaic vocabulary (cf. Professor Skeat's essay in Chatterton's Poems, Aldine ed., ii. xxx sq.)