"Enough here for the present," he announced, as he crawled out. "We shan't starve if we can carry enough away with us."

The frugal meal was eaten in silence. Uncle Brian produced a spirit flask, half filled with brandy. Pouring about a couple of tablespoonfuls of soda water into the metal cup, he handed it to his companion.

"Your liquid ration, Peter," he said solemnly. "We'll have to make it last out till we find water."

CHAPTER XVII

The Passage Perilous

No time was lost in making preparations for the long trek. Each man had to carry as much as he possibly could without impeding his movements. Uncle Brian took the remaining parts of the secret-ray apparatus, which he discovered lying in the sand undamaged and still in the haversack. The rest of his load consisted of a rifle and ammunition, a blanket and waterproof sheet, and about ten pounds of foodstuffs. Peter loaded himself up with his sleeping-bag, twenty pounds of provisions, the liquid compass from the flying-boat, a coil of light line, his automatic, matches, and—in anticipation of finding water—an empty water-bottle with slings attached.

"We shan't have to do very much climbing to get out of this," declared Uncle Brian. "And I shall be very disappointed if we don't find water within an hour or two. At one time this place was a mountain lake. The water has drained away—where? Not through the sand, because it's a certainty that the bed of the lake was hard rock similar to the surrounding mountains. It flowed away through a canyon. If we find the canyon we find our way of escape."

Peter agreed, but up to the present there was not the slightest visible sign of a gorge. The enclosing wall of rock seemed continuous, without a rift lower than five hundred feet above the plain.

Progress was slow. The sand, although tolerably firm, was hard going. The heat of the sun, coupled with the weight of their burdens, distressed both men severely.