Soon after his return from his northern expedition, Gregory was despatched in 1858 by the Government of New South Wales to search again for the lost explorer Leichhardt, who had then been missing ten years. This expedition resulted in little or nothing, as far as its main object was concerned, one or two trees, marked L, on the Barcoo and lower end of the Thompson, was all it discovered; but, geographically, it settled the question of the course of the Barcoo, or Mitchell's Victoria, which Gregory followed past Kennedy's farthest point, and traced until he found it identical with Sturt's Cooper's Creek. He described it as being of enormous width in times of flood, and two of Sturt's horses, abandoned since 1845, were seen but left uncaptured. Sturt's Strezletki Creek in South Australian territory was then followed. This peculiar watercourse branches out from the Cooper and runs in a south-south-west direction. It brought Gregory safely to the northern settlements of South Australia. The fruitless search for it, however, was one of the main causes of the death of Burke and Wills in 1861. This was Gregory's final attempt; he accepted the position of Surveyor-General of Queensland, and his labours as an explorer terminated. His journals are characterised by a brevity that is not the soul of wit, he appearing to grudge to others the information he had obtained at the expense of great endurance, hardihood, knowledge, and judgment. Gregory was probably the closest observer of all the explorers, except Mitchell, and an advanced geologist. In 1858 a new aspirant for geographical honours appeared on the field in the person of John McDouall Stuart, of South Australia, who, as before mentioned, had formerly been a member of Captain Sturt's Central Australian expedition in 1843-5 as draftsman and surveyor. Stuart's object was to cross the continent, almost in its greatest width, from south to north; and this he eventually accomplished. After three attempts he finally reached the north coast in 1862, his rival Burke having been the first to do so. Stuart might have been first, but he seems to have under-valued his rival, and wasted time in returning and refitting when he might have performed the feat in two if not one journey; for he discovered a well-watered country the whole way, and his route is now mainly the South Australian Transcontinental Telegraph Line, though it must be remembered that Stuart had something like fifteen hundred miles of unknown country in front of him to explore, while Burke and Wills had scarcely six. Stuart also conducted some minor explorations before he undertook his greater one. He and McKinlay were South Australia's heroes, and are still venerated there accordingly. He died in England not long after the completion of his last expedition.