Out into the open fields they went, but their search seemed likely to be in vain. Between times of looking for the water they scanned the sky for a sight of the projectile, which, hoping against hope, they thought they might see hovering over them. But there was no sight of it. They came to a vast, level plain, girt with mountains, a lonesome place, where there was no sign of life. Listlessly they walked over it. Suddenly Andy, who was in the lead, uttered a cry and sprang forward. 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.