Ludwig Leichhardt, a German explorer, born at Trebatsch, Prussia, Oct. 23, 1813, died in Australia in 1848. He studied at Gottingen and Berlin, being aided by William Nicholson, a physician of Bristol, whom he accompanied to France, Italy, and England, and who also enabled him to go to Australia in 1841. From Sydney he made several excursions into the interior, gathering much valuable information. A subscription amounting to £125 having been raised to fit out an exploring expedition under his charge, he left Moreton bay, on the E. coast, in August, 1844, with seven companions, crossed what is now the colony of Queensland and the S. part of York peninsula, rounded the gulf of Carpentaria, and reached the settlement of Victoria Dec. 17, 1845, whence he returned by water to Sydney, arriving March 29,1846. In October he again set out, hoping to find a direct passage across Australia to the N. coast; but he was repeatedly baffled, and was unable to carry out his project until December, 1847. His last letter was dated at Fitzroy Downs, W. of More-ton bay, April 8, 1848. Reports of his having been killed were received in 1850, and were confirmed in 1852 by the searching expedition of Hovenden Hely. In 1862 Conn and Giles discovered graves which were supposed to be those of Leichhardt and his companions; but new expeditions under Maclntyre in 1865 and Forrest in 1869 failed to throw light upon the fate of the explorer.

In 1872 the authorities of Sydney sent out Andrew Hume, who affirmed that in 1862 he had met with Classen, the brother-in-law of Leichhardt, and his second in command, at a native settlement near the head of Sturt's creek. Hume returned to Sydney in February, 1874, and reported that he had again met Classen with the same natives, who had in the mean time removed to the head waters of Fitzroy river. According to Hume's report of Classen's statement, Leichhardt's men mutinied at the head of Victoria river, and were afterward killed by the natives; Leichhardt dying from want five days after the mutiny, and being buried in a hollow tree, according to the custom of the natives, and the life of Classen being spared on account of his skill in medicine. Hume professed to have in his possession the watch and quadrant of Leichhardt, a portion of his diary, and a written statement drawn up by Classen. He also discovered a letter written by Leichhardt at Darling Downs, in February, 1848, in which he expressed great delight at receiving medals from the London and Paris geographical societies, and said that he was about to explore Victoria river.

Leichhardt wrote "Journal of an Overland Expedition in Australia, from Moreton Bay to Port Essington" (London, 1847; German translation by Zuchold, Halle, 1851), and Beitrage zur Geologie von Aus-tralien (Halle, 1855). His biography has been written by Zuchold (Leipsic, 1856).