Napier, JOHN, Laird of Merchiston, was born at Merchiston Castle, near Edinburgh, in 1550. He matriculated at St Andrews in 1563, and travelled for some time on the Continent, returning to his native country highly informed and cultivated; but, declining all civil employments, he preferred the seclusion of a life devoted to literary and scientific study. In 1593, however, he was one of a deputation of six to the king regarding the punishment of the 'Popish Rebels;' and in the same year he published his Plaine Discouery (or 'Interpretation') of the whole Revelation of Saint John (revised ed. 1611; 5th ed. 4to, 1645). In the dedication to King James VI. he gave his majesty some very plain advice regarding the propriety of reforming his 'house, family, and court;' and the work went through numerous editions in English, Dutch, French, and German. In July 1594 he made a contract with Logan of Restalrig for the discovery of treasure in East Castle. About this time he seems to have devoted much of his time to the invention of warlike machines for the defence of the country against Philip of Spain, and a list of the same exists at Lambeth Palace, dated 1596. Like other eminent men of the time, Napier, though a strict Presbyterian, seems to have been a believer in astrology and divination. In 1596 he proposed the use of salt as a fertiliser of land. In 1614 he first gave to the world his famous invention of Logarithms (q.v.), in a treatise entitled Mirifici Logarithmorum Canonis Descriptio (4to, Edin.). Napier's next work was Rabdologie seu Numerationis per Virgulas libri duo (Edin. 1617), detailing an invention for simplifying and shortening the processes of multiplication and division mechanically by means of the device subsequently known as Napier's
Bones—an arrangement of narrow slips of bone, ivory, metal, or pasteboard, inscribed with figures. This ingenious contrivance, however, was superseded by his logarithms. He also prepared a second work on logarithms, showing their mode of construction and application, with an appendix containing several propositions of spherical trigonometry, and those formulae which are now known by his name. This work was published after his death (4th April 1617) by his son Robert in 1619. There is an English translation by W. R. Macdonald, The Construction of the Wonderful Canon of Logarithms, with a catalogue of the various editions of Napier's works (1889). Napier's eldest son, Archibald, was raised to the peerage as the first Lord Napier by Charles I. in 1627, and his descendants still bear the title—the ninth Baron Napier having in 1872 become also Baron Ettrick in the peerage of the United Kingdom.
Two Lives of Napier have been published, the one by the Earl of Buchan (1787), and the other by Mark Napier (1834), who also edited Ars Logistica, 'The Baron of Merchiston his booke of Arithmeticke and Algebra' (1839), reprinted from a manuscript copy for the Bannatyne Club. This work had been originally transcribed from Napier's notes by his son Robert.