Mitchell, John (d.1768) (DNB00)
MITCHELL, JOHN (d. 1768), botanist, born and educated in England, graduated M.D., although at what university is uncertain. There were several John Mitchells at Oxford at the beginning of the eighteenth century, more than one at. Cambridge, and one who entered Leyden on 12 Feb. 1712, but none of these can be certainly identified with the botanist. Mitchell is said to have emigrated to America about 1700, and resided in Virginia, at Urbanna, on the Rappahannock river, about seventy-three miles from Richmond. He devoted himself to botanical and other scientific studies, and discovered several new species of plants, one of which was called after him, 'Mitchella repens,' by Linnæus. In 1738 he wrote a 'Dissertatio brevis de principiis botanicorum,' dedicated to Sir Hans Sloane, and in 1741 'Nova Plantarum genera,' dedicated to Peter Collinson [q. v.], both of which were subsequently printed at Nuremberg, 1769. In 1743 Mitchell prepared an 'Essay upon the Causes of the different Colours of People in different Climates,' which was read before the Royal Society by Peter Collinson at various meetings between 3 May and 14 June 1744, and published in the 'Philosophical Transactions ' (xliii. 102, &c.) It was designed as a solution of a prize problem set by the academy of Bordeaux. Mitchell maintains that the influence of climate and mode of life is sufficient to account for differences in colour.
Either in 1747 or 1748 Mitchell returned to England. On 17 and 24 Nov. 1748 his essay 'Of the Preparation and Use of various kinds of Potash' was read before the Royal Society (Phil. Trans, xlv. 541, &c.), and on 15 Dec. of the same year Mitchell himself became F.R.S. In December 1759 he contributed to the 'Philosophical Transactions a 'Letter concerning the Force of Electrical Cohesion,' dated from Kew. Mitchell died in March 1768. He must be carefully distinguished from John Michell (d. 1793) [q. v.], astronomer.
Besides the works already mentioned Mitchell published : 1. 'A Map of the British and French Dominions in North America,' London, 1755, which is said to 'mark an era in the geography' of North America, and was often quoted in boundary negotiations : a French version was published at Paris in 1756, and a second edition appeared in 1757, which was reprinted in 1782. There are copies of all in the British Museum Library. 2. 'The Contest in America between Great Britain and France, by an Impartial Hand,' London, 1757. 8vo. 3. 'The Present State of Great Britain and North America,' 1767, 8vo. He also left in manuscript 'An Account of the Yellow Fever which prevailed in Virginia in 1737, 1741, and 1742,' in letters to Cadwallader Colden and Benjamin Franklin, which were published, together with Colden's and Franklin's replies, by Professor Rush in the 'American Medical and Philosophical Register' (iv. 181 sgq.)
[Works in Brit. Mus. Library ; Lists of Fellows of the Royal Society, 1748-67; Phil. Trans, passim; Pulteney's Progress of Botany (with manuscript notes), ii. 278-81 ; Gent. Mag. 1768, p. 142; Miller's 'Retrospect of the Eighteenth Century, i. 318, ii. 367; Ramsay's Eulogy on Dr. Rush, pp. 84-5; Thacher's American Medical Biog. i. 392-3: Rich's Bibl. Amer. Nova, i. 36, &c. ; American Medical and Phil. Register, vol. iv.]