year he entered Emmanuel College, Cambridge, as a pensioner. Among his early recollections were visits to Sir Hans Sloane, then in extreme old age, bearing copies of his father's publications. At Cambridge Martyn studied classics under Hurd. He became Whichcote scholar in 1753, foundation scholar and Thorpe exhibitioner in 1755, and graduated as fifth senior optime in 1756, having no taste for mathematics. A student of botany from his childhood, he became familiar with the ‘Systema Naturæ,’ the ‘Genera Plantarum,’ and the ‘Critica Botanica’ of Linnæus on their first appearance; but, though he had been brought up by his father as a follower of Ray, the ‘Philosophia Botanica’ (1751) and ‘Species Plantarum’ (1753) converted him to those Linnæan views of which he became one of the earliest English exponents.
Martyn was elected fellow of Sidney Sussex College, and was ordained deacon in 1758, when he proceeded M.A., and priest in the following year. From 1760 to 1774 he acted as tutor of his college. On his father's resignation in 1762 he was elected university professor of botany, a post which he retained for sixty-three years, though he only lectured until 1796, botany not proving a very popular subject. Dr. Richard Walker, vice-master of Trinity College, having given the site of the monastery of Austin Friars for a botanical garden, Martyn became in the same year the first reader in botany under this endowment. In 1763 he gave his first course of lectures, basing them on the Linnæan system, to which Stillingfleet, Lee, Hill, and Hudson had already directed public attention, and which Hope was simultaneously introducing into the university of Edinburgh. In the same year he published his first work, ‘Plantæ Cantabrigienses,’ and spent the long vacation in Holland, Flanders, and Paris. In 1766 he graduated as B.D., and in 1770, on Charles Miller's departure for the East Indies, he began some years' gratuitous service as curator of the university garden, the funds being then at a low ebb.
In 1773, in conjunction with his fellow-tutor, John Lettice [q. v.], Martyn began the publication of ‘The Antiquities of Herculaneum,’ the Italian original of which they had bought for 50l. The Neapolitan court, however, sent a formal protest against the issue of this version of a work ‘designed exclusively for presentation,’ and only one part, containing fifty plates, was ever published. On Martyn's marriage at the close of this year he vacated his fellowship, and was presented by the bishop to the sequestration of Foxton, and went to live at Triplow, near Cambridge, where he took pupils till 1776. At the beginning of 1774 his pupil John Borlase Warren presented him to the rectory of Ludgershall, Buckinghamshire, and in 1776 to the vicarage of Little Marlow, which became his headquarters until 1784.
In 1778 he accompanied his pupil and ward, Edward Hartopp, of Little Dalby Hall, Leicestershire, for a two years' tour on the continent, taking with him his wife and infant son. After settling for some time at Vandœuvres, near Geneva, they went as far south as Naples, and returned to England by Venice, Tyrol, Cologne, and Brussels. Martyn kept a journal, part of which he afterwards published, and made a large collection of minerals to illustrate lectures on general natural history, with which he now found it expedient to supplement those on botany.
In 1784 he came to London for his son's education, and, having purchased the Charlotte Street Chapel, Pimlico, from Dr. Dodd, resigned the rectory of Ludgershall, in which he was succeeded by his half-brother, Claudius. At this time he produced his most popular work, his translation and continuation of Rousseau's ‘Letters on the Elements of Botany,’ which went through eight editions, and began his most considerable undertaking, his edition of Philip Miller's ‘Gardener's Dictionary.’ This was in fact an entirely new work on the Linnæan system, which he undertook in 1785 for Messrs. White & Rivington for a thousand guineas, expecting to complete it in eleven years. It was not, however, published as a whole until 1807.
In 1791, at the request of Sir J. B. Warren, he became secretary to the Society for the Improvement of Naval Architecture, which lasted until 1796, and in 1793, after thirty years' work, his professorship at Cambridge was made a royal one, and he was given a pension of 100l. per annum.
In 1798 he removed to Pertenhall rectory, Bedfordshire, the home of his cousin, the Rev. John King, who in 1800 resigned the living to the professor's son and only child, John King Martyn, fellow and mathematical lecturer of Sidney Sussex College, and the latter in 1804 resigned it to his father. Here Martyn passed the remainder of his life, his last literary work being to assist Archdeacon Coxe in his edition of Stillingfleet's ‘Tracts,’ 1811, and to contribute a list of plants to Manning and Bray's ‘History of Surrey,’ 1814. He continued to preach until eighty-two years of age, when his biographer, George Cornelius Gorham [q. v.], became his curate. He died at Pertenhall 3 June