Ainsworth was born on 9 November 1807 at
Exeter, the son of John Ainsworth of
Cheshire, captain in the 15th and 128th regiments. The novelist
William Harrison Ainsworth was his cousin; at his cousin's request he adopted the additional Christian name Francis, to avoid confusion.
In 1827 he became a licentiate of the
Royal College of Surgeons of Edinburgh, where he filled the office of president in the Royal Physical and the Plinian societies. He then went to London and Paris, where he became an intern at the
École nationale supérieure des mines. While in France he also gained practical experience of geology in the
Pyrenees. After studying at
Brussels he returned to Scotland in 1829 and founded, in 1830, the
Edinburgh Journal of Natural and Geographical Science, which was discontinued in the following year.
In 1831 there was an outbreak of
Sunderland; Ainsworth went there to study it, and published his experiences in Observations on the Pestilential Cholera, London, 1832. This book led to his appointment as surgeon to the cholera hospital of
St. George's, Hanover Square. On another outbreak, in Ireland he acted successively as surgeon of the hospitals at
In 1836 Ainsworth, after studying under Sir
Edward Sabine, was appointed surgeon and geologist to the expedition to the
River Euphrates under
Francis Rawdon Chesney. Shortly afterwards he was placed in charge of an expedition to the Christians of
Chaldaea, which was sent out by the
Royal Geographical Society and the
Society for Promoting Christian Knowledge. He went to
Asia Minor, the passes of the
Taurus Mountains, and northern
Mosul in the spring of 1840. During the summer he explored the
Kurdistan mountains and visited
Lake Urimiyeh in
Persia, returning through
Greater Armenia; and reached
Constantinople late in 1840. This expedition had financial troubles, and Ainsworth had to find his way home at his own expense.
After his return to England in 1841 Ainsworth settled at
Hammersmith, and assisted his cousin, William Harrison Ainsworth, in the conduct of several magazines, including
Bentley's Miscellany, and the
New Monthly Magazine. In 1871 he succeeded his cousin as editor of the New Monthly, and continued in the post until 1879.
For some years he acted as honorary secretary to the Syro-Egyptian Society, founded in 1844, and he was concerned to promote the Euphrates and Tigris valley route to India, with which Chesney's expedition had been connected. He was one of the founders of the
West London Hospital, and its honorary treasurer until his death at 11 Wolverton Gardens, Hammersmith, on 27 November 1896. He was the last survivor of the original fellows of the
Royal Geographical Society from its formation in 1830, was elected a
Fellow of the Society of Antiquaries on 14 April 1853, and was also a corresponding member of several foreign societies. He married, and left a son and two daughters.