MITCHELL. Sir THOMAS T.TVINGSTONE, 1792-1855; b. Scotland; son of John Mitchell. His family altered its name 'of Mitchell upon its intermarriage with the Liv ing.stones Thomas Mitchell began his service in the British army in the Portugal cam paign of 1808, and at the close of the peninsular war had been promoted maj. He was then sent to make surveys and plans of the peninsular battle-fields. In 1827 he published Outlines of a System of Surveying for Geographical and Military Purposes, and was made deputy- surveyor-general of New South Wales. Besides the routine work of this office, he led a number of exploring expeditions into the interior of Australia. In 1831-32 lie discovered the Pell river and the Nammoy. In 1835 he traced the course of she river Darling, which he followed, in 1836, as far as the _Murray river, with which it unites. In the same expedition he followed the Glenelg river to the ocean. He gave the world the remits of his explorations in his Three Expeditions into the Interior of East ern Australia, etc., which appeared in 1838. He came to England to take charge of this
work and of his Map of the Colony of New South Wales in their passage through the . press, and on the occasion of this visit was knighted. He also received the degree of D.C.L. from Oxford, and was elected to the royal and the geographical societies. On his return to Australia lie conducted a fourth exploring expedition, in which he reached 21° 30' south. He followed the Victoria river, which he was the first to find and name, but failed to advance as far as the gulf of Carpentaria. on account of losing his horses from a continued drought. In 1850 he published a school geography for use in New South Wales under the name of Australian Geography. Ills next publication was an account of a new steam propeller which he had invented on the principle of the boom erang. This work was published as the The History, and Description of the Boom erang Propeller. In 1854 he was made a col.