By this time the gold rush to the southern portion of Western Australia had set in strong, and the country that had so long repelled the pastoral pioneer by its aridity was now overrun with prospectors, their camps supplied with water by condensers at the salt lakes and pools. At first the loss of life was very great; for it was not likely that a district that could be safely traversed only by the hardiest and most experienced bushmen would freely yield its secrets to untried men. Of the many deaths that occurred from thirst, no complete record will ever be available. Some unrecognisable and mummified remains may some day be found amid the untrodden waste; but few have yet been tempted to break in upon the solitude of the dead men of the desert. As the southern goldfields spread and became thickly-populated, the food supply was an important question, and men's eyes naturally turned to the well-stocked northern stations, from which many cattle were being sent south by steamer. Though the distance overland was not prohibitive, the belt of desert country that intervened, upon which Warburton to his sorrow was the first to venture, forbade the passage of stock. This belt of Sahara extended, roughly speaking, from the eastern border of the colony to the head waters of the western coastal rivers. North and south it lay between the parallels of 19 degrees and 31 degrees south. As yet no daring attempt had been made to traverse its barren confines from south to north. But, to the born explorer, difficulty and danger give an added zest to geographical research; and in the year 1896 two separate expeditions sought to cross this dreadful zone. Both left civilization within a few days of each other. The first to start was known as the Calvert Expedition, from its originator. It was under L.A. Wells, the South Australian surveyor who had been the energetic second of the former Elder Expedition. The other was equipped and led by the Honourable David Carnegie.