Born in Manchester, March 5th, 1783, the son of Jeremiah Ainsworth, an accomplished scholar and well-known mathematician, who may be regarded as founder of a Lancashire school of mathematicians, and to whom many references will be found in *Notes and Queries*, 1853, viii, 541. The family of Ainsworth, an ancient one in Lancashire, was originally seated in the township of that name. Their arms are still visible over an archway in Plessington Hall, and by their alliances they acquired feudal estates in the county. Several interesting Ainsworths are mentioned in the *Dictionary of National Biography*. Henry Ainsworth, traveller and hebraist, was born at Plessington in 1560. Another learned ancestor was Robert Ainsworth, FAS, author of the standard Latin Dictionary, first published in 1736. Young James Ainsworth, who is one of the earliest born of the Fellows, carried his weight of hereditary linguistic faculty to the Free Grammar School, Manchester, and studied under Mr Lawson, head master, whose colleagues were Messrs Durbey, Pedley, and Holt. On leaving school he became a private pupil of the eccentric but able Rev Joshua Brookes, who was the son of a crippled shoemaker and of whom many delightful stories were told. In 1798, when only 15 years old, Ainsworth became an apprenticed pupil at the Manchester Infirmary, it being stipulated in his indentures that he should be allowed part of each day to go and take his lessons. Thus he studied the Latin classics and acquired a life-long taste for reading. After serving his apprenticeship he was for a short time Clerk at the Infirmary and acted as House Apothecary for nearly a year, during which an epidemic of fever raged and he almost died of the complaint. Some eminent surgeons were then at the Infirmary, such as Charles White and Benjamin Gibson, the oculist, to whose only child Ainsworth was afterwards guardian. From Manchester he went to Edinburgh, and at the University was the intimate friend of Henry Peter Brougham, afterwards Lord Brougham. When he had finished his training he was already a man of recognized ability, and was invited to enter into partnership with Thomas Henry, maker of calcined magnesia and other valuable chemical preparations. In 1806, at the early age of 23, he was elected Surgeon to the Manchester Infirmary, and held office until 1847, when he became Consulting Surgeon. He was also at one time Consulting Surgeon to the Workhouse. There appears to be some doubt as to who first started the medical schools of Manchester. Ainsworth is stated to have been the first to commence anatomical lectures in Manchester, which he began in conjunction with John Atkinson Ransome (q.v.), and he may therefore be regarded as the originator of what has since become the Royal School of Medicine and Surgery, Pine Street. It is worthy of notice, as one of the ‘small beginnings’, that Ainsworth converted the hay-loft over his stable into a lecture theatre. He was most indefatigable and enthusiastic in the pursuit of professional knowledge, and an exceedingly skilful manipulator. Some of his preparations, we are assured, are not to be surpassed, even at the present time. As an instance, we may mention an injected preparation of a large mastiff dog in which all the principal arteries of the body (with the sole exception of the aorta) had been successfully secured by ligature, without destroying the animal’s life. Ainsworth was, indeed, regarded as one of the ablest operators of his day in Manchester. He was among the founders of the Manchester Natural History Society, and of the Botanical and Horticultural Society, and always took a great interest in their progress and in the museum and gardens. In January, 1805, he became a member of the Manchester Literary and Philosophical Society, and at the time of his death nearly half a century later was one of its two oldest surviving members. “In conjunction with the late Mr Thomas Fleming and others, he was one of the revivers of an old Manchester club, which in its days was famous, under the appellation of ‘John Shaw’s’, from the name of the landlord, who is said to have enforced early hours upon his guests by the cracking of a large horsewhip at a fixed time. This club, which still exists, may be regarded as the only link between the social and convivial institutions of ‘Old Manchester’ and those of the present day.” Ainsworth was most hospitable and his large charity was scrupulously unostentatious, and “indeed carefully kept from the knowledge of the world”. He died at his residence, Cliff Point, Lower Broughton, Manchester, on Friday, Oct 28th, 1853, leaving a widow and one son, Dr Ralph Ainsworth. There is a portrait at the Royal Infirmary painted by George Withington. PUBLICATION:- *Syllabus of a Course of Lectures on Anatomy and Physiology*. Conjointly with J A RANSOME. Manchester, 1812.