Page:Dictionary of National Biography volume 23.djvu/46

Greaves   GREAVES, JOHN (1602–1652), mathematician, eldest son. of the Rev. John Greaves, rector of Colemore, near Alresford in Hampshire, was born at Colemore in 1602, and was sent to Balliol College, Oxford, in 1617. He graduated B.A. in 1621; was elected to a fellowship at Merton College in 1624; and proceeded M.A. in 1628. His taste for natural philosophy and mathematics led him to form an intimate acquaintance with Henry Briggs [q. v.], Dr. John Bainbridge [q. v.], and Peter Turner, senior fellow of Merton. He learned the oriental languages, and studied the ancient Greek, Arabian, and Persian writers on astronomy, besides Copernicus, Regiomontanus, Purbach, Tycho Brahe, and Kepler.

In 1630 he was chosen professor of geometry in Gresham College, London, continuing to hold his fellowship at Merton, and by Peter Turner was introduced to Archbishop Laud. In 1635 he appears to have visited Paris and Leyden, and to have formed a friendship with James Golius, and it is probable that he on this occasion extended his travels into Italy. In 1637 he went from Leghorn to Rome, and took measurements of several of the monuments there, particularly Cestius's Pyramid and the Pantheon. From Rome he went to Padua and Florence, and afterwards sailed from Leghorn to Constantinople, where he arrived in 1638. He was assured by some of the Greeks that the library which formerly belonged to the christian emperors was still preserved in the sultan's palace, and he procured thence Ptolemy's 'Almagest,' 'the fairest book he had ever seen.' From Constantinople he went to Egypt, touching on his way at Rhodes, and stayed four months at Alexandria. Hence he went twice to Cairo, with divers mathematical instruments, in order to measure the pyramids. Having made a collection of Greek, Arabic, and Persian manuscripts, besides a great number of coins, gems, and other valuable curiosities, he returned to Leghorn in 1639. After visiting Florence and Rome, he returned to England in 1640. On the death of John Bainbridge he was chosen Savilian professor of astronomy at Oxford, but was deposed from his professorship at Gresham College on the ground of his absence. In 1645 he drew up a paper for reforming the calendar by omitting the bissextile day for forty years to come; but his scheme was not adopted.

In 1646 he published his 'Pyramidographia, or a Discourse of the Pyramids in Egypt,' which was sharply criticised by Hooke and others. In 1647 he published 'A Discourse of the Roman Foot and Denarius,' which is highly commended by Edward Bernard [q.v.] in his 'De Mensuris et Ponderibus Antiquorum,' 1683. Greaves published in 1648 'Demonstratio Ortus Sirii Heliaci pro parallelo inferioris Ægypti,' as a supplement to John Bainbridge s 'Canicularia,' which he appears to have edited.

In 1642 Greaves was appointed subwarden of Merton; and in 1645 took the lead in promoting a petition to the king against Sir Nathaniel Brent [q. v.], who was thereupon deposed. On 30 Oct. 1648 Greaves was ejected by the parliamentary visitors from his professorship of astronomy and his fellowship at Merton on several charges, especially that of having made over 400l. from the college treasury to the king's agents. He was also charged with having misappropriated college property, having feasted with the queen's confessors, and having displayed favouritism and political animus in the appointment of subordinate college officers. Dr. Walter Pope discusses these charges at considerable length in his 'Life of Seth Ward,' 1697.

Greaves lost a large part of his books and manuscripts on this occasion ; some were recovered for him by his friend Selden. He then retired to London, where he married. In 1649 he published 'Elementa Linguæ Persicæ,' to which he subjoined 'Anonymus Persa de Siglis Arabum et Persarum Astronomicis,' astronomical tables employed by these races; and in 1650 'Epochæ celebriores, astronomis, historicis, chronologicis, Chataiorum, Syro-Græcorum, Arabum, Persarum, Chorasmiorum usitatæ, ex traditione Ulug Beigi,' to which is subjoined 'Chorasmiæ et Mawaralnahræ, hoc est, regionum extra fluvium Oxum descriptio ex tabulis Abulfedis, Ismaelis, Principis, Hamali.' In the same year was published his 'Description of the Grand Seignor's Seraglio,' reprinted, along with the 'Pyramidographia' and several other works, in 1737. In 1650 he published 'Astronomica quædam ex traditione Shah Cholgii Persæ, una cum Hypothesibus Planetarum,' and in 1652 'Binæ Tabulæ Geographicæ, una Nessir Eddini Persæ, altera Ulug Beigi Tatari,' eminent Persian and Indian mathematicians. Greaves died 8 Oct. 1652, and was buried in the church of St. Benet Sherehog in London.

The following works were posthumous: 1. 'Lemmata Archimedis e vetusto codice manuscripto Arabico,' 1659. 2. 'Of the Manner of Hatching of Eggs at Cairo,' 1677. 3. 'Account of some Experiments for trying the Force of Guns,' 1685. 4. 'Reflections on a Report to the Lords of the Council,'