During his excursions in various directions, Giles discovered and traversed four different ranges of hills.  The party were much worried by the hostility of the blacks, and, what with the uneasiness caused by their attacks, the plague of myriads of ants, the loss of Gibson, and the failure of their own hopes, they were forced to return to Adelaide, baffled for a time, but not beaten.

We thus see how the arid belt of the middle country had defied three different explorers —­ Warburton, Gosse, and Giles —­ one equipped with camels only, one with camels and horses, and one who had relied on horses alone.

[Illustration.  A Camel Caravan in an Australian Desert.]

In 1875 Giles took the field once more.  This time, owing to the generosity of Sir Thomas Elder, of South Australia, he was well-prepared.  He had a fine caravan of camels, and had his former companion Tietkins with him, besides a completely-equipped party.

The start was made from Beltana, the next halting-place being Youldeh, where a depot was formed.  From this place they shifted north to a native well, Oaldabinna.  As the water supply here proved but scanty, Giles started off to the westward to search for a better place, sending Tietkins to the north on a similar errand accompanied by Young.

Giles pushed his way for 150 miles through scrub and past shallow lakelets of salt water until he came to a native well or dam, containing a small supply of water.  Beyond this he went another 30 miles, but finding himself amongst saline swamps and scrub, he then returned to the depot.  Tietkins and his companion were not so successful.  At their furthest point they had come across a large number of natives, who, after decamping in a terrified manner, returned fully armed and painted for war.  No attempts of the two white men to open friendly communication or to obtain any information from them had succeeded.

A slight shower of rain having replenished the well they were camped at, Giles determined to make a bold push to the west, trusting to the powers of endurance of his camels to carry him on to water.

On reaching the dam that he had formerly visited, he was agreeably surprised to find that it had been nearly filled by the late rains.  As it now contained plenty of water for their wants, and there was good feed all around, they rested by it until the supply of water began to show signs of declining.

On the 16th of September, 1875, he left the Boundary Dam, as he called it, and commenced to try conclusions with the desert to the westward.  For the first six days of their march the caravan passed through scrubs of oak, mulga, and sandalwood; next they entered upon vast plains well-grassed, with salt-bush and other edible shrubs growing upon them.  Crossing these, the camel train again passed through scrub, but not so dense as before.

When 250 miles had been accomplished, Giles distributed amongst the camels the water he had carried with him.  As they kept on, sand-ridges began to make their appearance, native smoke was often seen, and they frequently crossed the tracks of the natives.