Then he was in and had laid him on the deck. Morrie was still out. He tried to remove the suit with trembling, glove-hampered fingers, then hastily got out of his own suit and un-clamped Morrie's helmet. No sign of life showed as the fresh air hit the patient.

Cussing bitterly he tried to give the boy oxygen directly from his suit but found that the valve on Morrie's suit, for some reason, refused to respond. He turned then to his own suit, disconnected the oxygen line and fed the raw oxygen directly to the boy's face while pushing rhythmically on his chest.

Morrie's eyes flickered and he gasped.

"What happened? Is he all right?" The other two had come through the lock while he worked.

"Maybe he is going to be all right. I don't know."

In fact he came around quickly, sat up and blinked his eyes. "Whassa matter?" he wanted to know.

"Lie down," Cargraves urged and put a hand on his shoulder.

"All right... hey! I'm inside."

Cargraves explained to him what had happened. Morrie blinked. "Now that's funny. I was all right, except that I was feeling exceptionally fine-"

"That's a symptom."

"Yes, I remember. But it didn't occur to me then. I had just picked up a piece of metal with a hole in it, when-"

"A what? You mean worked metal? Metal that some one made-"

"Yes, that's why I was so ex-" He stopped and looked puzzled. "But it couldn't have been."

"Possible. This planet might have been inhabited... or visited.

"Oh, I don't mean that." Morrie shrugged it off, as if it were of no importance. "I was looking at it, realizing what it meant, when a little bald-headed short guy came up and...ut it couldn't have been."

"No," agreed Cargraves, after a short pause, "it couldn't have been. I am afraid you were beginning to have anoxia dreams by then. But how about this piece of metal?"

Morrie shook his head. "I don't know," he admitted "I remember holding it and looking at it, just as clearly as I remember anything, ever. But I remember the little guy just as well. He was standing there and there were others behind him and I knew that they were the moon people. There were buildings and trees." He stopped. "I guess that settles it."

Cargraves nodded, and turned his attention to Morrie's oxygen pack. The valve worked properly now. There was no way to tell what had been wrong, whether it had frosted inside when Morrie walked on into the deeper shadows, whether a bit of elusive dirt had clogged it, or whether Morrie himself had shut it down too far when he had reduced pressure at Cargraves' suggestion and thereby slowly suffocated himself. But it must not happen again. He turned to Art.

"See here, Art. I want to rig these gimmicks so that you can't shut them off below a certain limit. Mmmm...o, that isn't enough. We need a warning signal too—something to warn the wearer if his supply stops. See what you can dream up."

Art got the troubled look on his face that was habitual with him whenever his gadget-conscious mind was working at his top capacity. "I've got some peanut bulbs among the instrument spares," he mused. "Maybe I could mount one on the neck ring and jimmy it up so that when the flow stopped it would-" Cargraves stopped listening; he knew that it was only a matter of time until some unlikely but perfectly practical new circuit would be born.

THE TOP OF THE RING OF HILLS showed them the earth, as Morrie had thought. Cargraves, Art, and Ross did the exploring, leaving Morrie back to recuperate and to work on his celestial navigation problem. Cargraves made a point of going along because he did not want the two passengers to play mountain goat on the steep crags—a great temptation under the low gravity conditions.

Also, he wanted to search over the spot where Morrie had had his mishap. Little bald men, no; a piece of metal with a hole in it—possible. If it existed it might be the first clue to the greatest discovery since man crawled up out of the darkness and became aware of himself.

But no luck—the spot was easy to find; footprints were new to this loose soil! But search as they might, they found nothing. Their failure was not quite certain, since the gloom of the crater's rim still hung over the spot. In a few days it would be daylight here; he planned to search again.

But it seemed possible that Morrie might have flung it away in his anoxia delirium, if it ever existed. It might have carried two hundred yards before it fell, and then buried itself in the loose soil.

The hill top was more rewarding. Cargraves told Art that they would go ahead with the attempt to try to beam a message back to earth... and then had to restrain him from running back to the ship to get started. Instead they searched for a place to install the "Dog House".

The Dog House was a small pre-fab building, now resting in sections fitting snugly to the curving walls of the Galileo. It had been Ross's idea and was one of the projects he and Art had worked on during the summer while Cargraves and Morrie were training. It was listed as a sheet-metal garage, with a curved roof, not unlike a Quonset hut, but it had the special virtue that each panel could be taken through the door of the Galileo.

It was not their notion simply to set it up on the face of the moon; such an arrangement would have been alternately too hot and then too cold. Instead it was to be the frame for a sort of tailor-made cave.

They found a place near the crest, between two pinnacles of rock with a fairly level floor between and of about the right size. The top of one of the crags was easily accessible and had a clear view of earth for line-of-sight, beamed transmission. There being no atmosphere, Art did not have to worry about horizon effects; the waves would go where he headed them. Having settled on the location, they returned for tools and supplies.

Cargraves and Ross did most of the building of the Dog House. It would not have been fair to Art to require him to help; he was already suffering agonies of indecision through a desire to spend all his time taking pictures and an equally strong desire to get his set assembled with which he hoped to raise earth. Morrie, at Cargraves' request, stayed on light duty for a few days, cooking, working on his navigation, and refraining from the strain of space-suit work.

The low gravitational pull made light work of moving the building sections, other materials, and tools to the spot. Each could carry over five hundred pounds, earth-weight, of the total each trip, except on the steeper portions of the trail where sheer bulk and clumsiness required them to split the loads.

First they shoveled the sandy soil about in the space between the two rocks until the ground was level enough to receive the metal floor, then they assembled the little building in place. The work went fast; wrenches alone were needed for this and the metal seemed light as cardboard. When that was done, they installed the "door," a steel drum, barrel-sized, with an air-tight gasketed head on each end.

Once the door was in place they proceeded to shovel many earth-tons of lunar soil down on top of the roof, until the space between the rock walls was filled, some three feet higher than the roof of the structure. When they were finished, nothing showed of the Dog House but the igloo-style door, sticking out between the rocky spires. The loose soil of Luna, itself a poor conductor of heat, and the vacuum spaces in it, would be their insulation.

But it was not yet air-tight. They installed portable, temporary lights, then dragged in sealed canisters and flat bales. From the canisters came sticky, tacky sheets of a rubbery plastic. This they hung like wallpaper, working as rapidly as possible in order to finish before the volatiles boiled out of the plastic. They covered ceiling, walls and floor, then from the bales they removed aluminum foil, shiny as mirrors, and slapped it on top of the plastic, all except the floor, which was covered with heavier duraluminum sheets.