"Mirage! Then it isn't water?"

"Water? No; only a peculiar effect seen in the atmosphere over a heated plain. We shall see no water till we near the mountains on the other side. But there, talk as little as you can, and avoid this heated dust which rises from the mules' hoofs."

"It's wonderful!" cried Ned thoughtfully. "I felt sure that we were near a beautiful lake."

"Such as deceives travellers sometimes."

"Ah, it's bad," said Griggs, "when you're crossing a plain, choking with thirst, and the water-bottles are empty. A sight like that has driven men mad before now with disappointment."

The boys recalled these words over and over again during their journey, for from the very first they realised what a tramp through such a desert meant--the sun came down with scorching power, and it was reflected up from the white sand and salt. At mid-day when they halted where there was no shadow but that cast by their four-footed companions, there was not a breath of air, and the poor brutes stood with hanging heads and drooping ears, panting and even sighing, while when the evening drew near the wind swept boisterously over the plain, but brought no refreshment, for not only was it hot, but it wafted up the fine, irritating dust and produced additional sensations of thirst.

The march was kept on long after sundown, when another halt was made for refreshment; but there seemed to be none, for the amount of water used was small in the extreme, and after about an hour's wait, during which the baggage animals had been relieved of their burdens, the doctor rose.

"Now then," he said sternly, "load up. We must keep on all through the night, and refresh again at daybreak."

"Refresh!" said Wilton dismally.

"Well, rest the mules," replied the doctor. "Then go on again for three or four hours and try and sleep through the hottest part of the day."

"What about keeping our course correctly through the night?" said Bourne.

"There are the stars," replied the doctor, pointing up to the clear sky.

"I know exactly what to do. We must keep on now we have started, and bear it like men."

No one spoke, but "buckled to," as Griggs called it, and to relieve the horses the party tramped by their side for the greater part of the night, during the early hours of which Chris grew more and more sleepy; but as they approached "night's dull noon," he grew more wakeful and relieved the tedium by talking to first one and then the other cheerfully enough, and never at a loss for something to say.

"It might be worse, Ned," he said once during the night.

"Couldn't be," was the surly reply.

"Oh, couldn't it! It might come on to rain tremendously. Well, what are you laughing at?" he continued, for Griggs burst out into a hoa.r.s.e guffaw.

"You," replied the American. "Don't I wish it would rain! Why, it would cool everything. No, I don't know that, for the earth's so hot that all day to-morrow we should be in the midst of steam. It would refresh the horses and mules, though. Nice place this, isn't it?"

"Horrible! What's the use of having all this desert?"

"Don't know," said Griggs bluntly. "You tell me what's the use of having all that sea, and then perhaps I'll tell you."

They relapsed into silence then, and the monotonous tramp went on.

There was no kicking or squealing among the mules. Skeeter tramped on with his bell going _clang_--_clang_--_clang_--_clang_, in accompaniment to his steps, and the other mules followed as if walking like so many shadows in their sleep, while the ponies seemed to follow their masters like dogs, ready to accept every pat on the neck or word of encouragement, and after raising their muzzles to the offered hand and looking through the darkness appealingly, as if asking how long it would be before they came to water.

Morning at last. A halt, packs lowered to the ground, each animal's mouth washed out with about a pint of the precious fluid--water, and then their ration given in the form of very stiff gruel.

All this carefully done before the breakfast was attacked.

"I don't call it a breakfast," grumbled Ned.

"No, I wouldn't," said Chris. "Cheer up; we haven't so far to go now as we had yesterday morning."

"Well, I know that," snarled Ned, who seemed all on edge. Chris called it gritty, and said it was the sand--to himself.

"He gets it on his temper," thought the boy. "How queer it is that being hot and tired and thirsty makes any one so cross."

"Forward!" said the doctor at last, when the packs had been readjusted; and the dreary tramp began again, with the sun getting hotter and hotter every hour.

"Oh dear!" groaned Ned, as they tramped side by side, each with his hand resting upon his pony's neck and holding on by the mane. "That miserable tinful of water! Why, it was only half-a-pint, and it will be hours before we're allowed any more. Why not let us have a pint all at once?"

"Against the rules," said Chris. "You should have made believe, as I did."

"Believe what?"

"No, I didn't believe it," said Chris; "I only played at it. I drank my half-pint very slowly, and pretended it was a pint. You do the same the next time."

"Not going to be such a fool," said Ned gruffly. "It's all too real to play. Bother! Hang it! Yah! I wish there wasn't a sc.r.a.p of gold in the world."

"But there is, all the same. Come, cheer up, lad."

"Cheer down, you mean. It's getting worse and worse, and I don't believe we shall ever get across this horrible plain. What is there to be cheerful about?"

"Well, here's one thing--we've got away from the Indians. There isn't a sign of them behind."

"Of course there isn't," grumbled Ned. "Indians are not such idiots as to come across a place like this."

"Griggs says they do sometimes."

"I don't believe it; they must always go round. Oh, I do wish we hadn't come."

Somehow or other, the more low-spirited and doleful Ned became, the more hopeful and cheery Chris seemed. Perhaps it was what he called make-believe, and put on by a great effort, but he was the brightest of the party and brought a smile to the lip of every one in turn with his light, trivial remarks, all of which, however, had a suggestion that, in spite of their terrible sufferings, he was looking at the best side of things.

"I say, father," he cried, as mid-day was approaching, "this is a better desert than the other one we crossed."

"I don't see much difference, my boy. Why do you think so?"

"It's so nice and smooth. You don't have to keep stumbling over stones."

"But that's a fault, boy," said his father. "Some of those great stones cast a little shade. Here we have none. Halt!" he cried loudly. "Four hours' rest and sleep."

The mules were unloaded, the ponies' saddles removed, and the tent-sheet was spread over the horizontal raised pole for shade, such as it was; and then no one thought of how, but lay down to sleep, lying motionless till the doctor summoned them again for the resumption of the march, when all began to compare notes.

"Sleep? No, I never had a wink," said Ned. "Who could sleep, with the sun seeming to burn a hole in that canvas?"

"I didn't go to sleep either," said Chris; "but one feels a bit rested with lying down."

"No, one don't," said Ned; and the weary tramp went on, with nothing visible in front of the overstrained eyes but the glare, and a thick misty look as if the atmosphere was full of hot, dusty sand.

The pace at which they went on appeared to be slower, but it was the party's want of perception which diminished and magnified at the same time, princ.i.p.ally the latter, in making the journey appear longer than it really was, while that hot afternoon went on in a nightmare-like waking dream which made Ned complain at last that he was going off his head.

"I'm not," said Chris, laughing. "I feel as if I'm always going off my legs."