Thomas, a philologist, was the son of a riding-master, and was born in London in 1783. From Christ's Hospital he passed as an exhibitioner to Pembroke College, Cambridge, in 1802. As he did not enter into orders, a fellowship which he subsequently obtained at Sidney Sussex College was taken from him at the end of a limited period, and he was forced to support himself by private tuition and by writing for the press. Several essays in the Quarterly Review on Aristophanes, and a metrical translation of the plays of that poet, were the groundwork of Mitchell's reputation. These were followed by editions of five dramas of Aristophanes and the entire works of Sophocles. Mitchell died at his house near Woodstock in 1845.

Sir Thomas Livingstone, one of the most successful explorers of Australia, was the son of Mitchell of Craigend in Stirlingshire, and was born there in 1792. From 1808 till the end of the Peninsular War he served in Wellington's army. He was then raised to the rank of major, and employed by government to make surveys of the great battlefields in the Peninsula. At a later period the office of surveyor-general of New South Wales was conferred upon him. In this capacity, between 1831 and 1836, he led three exploring expeditions into the interior of Australia, undergoing great hardships, and exposing himself to imminent peril, yet sedulously collecting all possible information, both on geography and natural history. The results of these journeys were the discovery of the Peel River, the Namoy, and Australia Felix, and the exploration of the courses of the Darling and the Glenelg. Major Mitchell published an account of his three expeditions, in 2 vols. 8vo, London, 1838. While in England superintending this publication he was knighted by the Queen, and received the title of D.C.L. from the university of Oxford. His last great exploring tour was begun towards the close of 1845, and aimed at discovering a route between Sidney and the Gulf of Carpentaria. The result was published in his Journal of an Expedition into the Interior of Tropical Australia, 8vo, London, 1848. Sir Thomas Mitchell died at Sydney in October 1855, and was honoured with a public funeral.