The boys ran to him, and found the old hunter gazing into the depths of a great black pool, which filled a depression in the surface of the moon. It was a small crater, and was filled, nearly to the top, with some black liquid, which gloomily reflected back the light of the sun.

"I'm going to have a drink!" cried Andy, and before the boys could stop him he threw himself face downward at the edge of the black pool.

CHAPTER XXVIII

THE SIGNAL FAILS

"Stop! Don't drink that! It may be poison!" yelled Jack.

"Pull him back!" shouted Mark, and together they advanced on the old hunter. They tried to drag him away from the black pool, but Andy shook them off.

"Let--me--alone!" he gasped, as he bent over the uninviting liquid and drank deeply. "It's water, I tell you--good water--and I'm almost--dead--from--thirst!"

"Water? Is that water?" cried Jack.

"Well, it's the nearest thing to it that I've tasted since I've been lost on the moon," spoke Andy, as he slowly arose. "My, but that was good!" he added fervently.

"But--water?" gasped Mark. "How can there be water here?"

"Taste and see," invited the old hunter.

They hesitated a moment, and then followed his example. The liquid--water it evidently had once been--had a peculiar taste, but it was not bad. By some curious chemical action, which they never understood, the liquid had been prevented from evaporating, nor was it frozen or petrified as was everything else on the moon.

What gave the liquid its peculiar black color they could not learn.

Sufficient for them that it was capable of quenching their thirst, and they all drank deeply and refilled their bottles.

"Now, I feel like eating again," spoke Andy, "We can take some of this back with us, and have a good meal on blasted meat. Whenever we get thirsty we'll have to make a trip back here for water."

The boys agreed with him. They examined the black pool. It appeared to be filled by hidden springs, though there was no bubbling, and the surface was as unruffled as a mirror. The liquid was not very inviting, being as black as ink, but the color appeared to be a sort of reflection, for when the water, if such it was, had been put into bottles it at once became clear, nor did it stain their faces or hands.

"Well, it's another queer thing in this queer moon," said Jack. "I wish the two professors could see this place. They'd have lots to write about."

"I wonder if we'll ever see them again?" asked Mark.

"Sure," replied Jack hopefully. "We'll fill our lunch baskets, take a lot of water along, and have another hunt for the projectile soon."

They did, but with no success. For several days more they lived in the petrified city, the meat encased in its block of stone, which Andy blasted from time to time, and the black water keeping them alive. From time to time they went out in the surrounding country, looking for the projectile. But they could not find the place where they had left it, nor could they find even the place where they had picked up the lost tool that had cost them so much suffering. They were more completely lost than ever. They crossed back and forth on the bridge over the crater chasm, and penetrated for many miles in a radius from that, marking their way by chipping off pieces of the rocky pinnacles, as they did not want to leave the petrified city behind.

From some peaks they caught glimpses of other towns that had fallen under the strange spell of the petrification. Some were larger and some smaller than the one they called "home."

Jack proposed visiting some of them, thinking they might find better food, but Mark and Andy decided it was best to stay where they were, as they were nearer the supposed location of the projectile.

"I think they'll manage to fix it up somehow, so it will move," said Andy, "and then they'll come to look for us. I hope it will be soon, though."

"Why?" asked Jack, struck by something in the tone of the old hunter.

"Because," replied Andy, "I am afraid our life-torches won't last much longer. Mine seems to be weakening. I have to hold it very close to my face now to breathe in comfort, while at first the oxygen from it was so strong that I could hold it two feet off and never notice the poisonous moon vapors."

This was a new danger, and, thinking of it, the faces of the boys became graver than ever. Death seemed bound to get them somehow.

Two more days went by. They had now been lost on the moon over a week.

Each one now noticed that his life-torch was weakening. How much longer would they last? They dared not answer that question. They could only hope.

The sun, too, was moving away from them. Soon the long night would set in. By Mark's computation there was only three more days of daylight left. What would happen in the desolate darkness?

As they were returning from the black pool, with their water bottles filled, and put inside the fur bags to prevent the frost from reaching them, Mark happened to gaze over across a line of towering peaks. What he saw caused him to gasp in astonishment.

"Jack! Andy! See!" he whispered hoa.r.s.ely, pointing a trembling finger at the sky.

There, outlined against the cloudless heavens, was a long, black shape, floating through the air about two miles distant.

"The projectile! The _Annihilator!_" yelled Jack. "Shout! Call to them!

Wave your hands! Andy, fire your gun! They have started off, and they can't see us. We must make them hear!"

Together they raised their voices in a mighty shout. The old hunter fired his gun several times. They waved their hands frantically.

But the projectile never swerved from its course. On it moved slowly, those in it paying no heed to the wanderers, for they did not hear them. Andy fired his gun again, but the signal failed, and a few minutes later the _Annihilator_ was lost to sight behind a great peak.

CHAPTER XXIX

THE FIELD OF DIAMONDS

Dumbly the wanderers gazed at each other. They could not comprehend it at first. That the projectile, on which their very lives depended in this dead world of the moon, should float away and leave them seemed incredible. Yet they had witnessed it.

"Do--do you really think we saw it--saw the _Annihilator_, Mark?" asked Jack in a low voice, after several minutes had pa.s.sed.

"Saw it? Of course, we saw it. We've seen the last of it, I'm afraid.

But what do you mean?"

"I--I thought maybe I was out of my head, and I only saw a vision,"

answered Jack. "You know--a sort of mirage. It was real, then?"

"Altogether too real," spoke Andy Sudds grimly. "They didn't see us nor hear us. We're left behind!"

"But can't we do something?" demanded Mark. "Let's start off and try to catch them. They were going slow."

"The wonder to me is how they moved at all," said Jack. "I thought the machinery wouldn't work until we got back with the lost tool."

"Probably the two professors found some way of patching up the motor,"

was Mark's opinion, and later they found that this was so.