THE valve had ceased to hiss when Winslow opened it wide. The air in their cabin was thin; their lungs labored heavily at first. Jerry felt as he had felt more than once at some great elevation on earth. But they lived, and they could breathe, and they were about to do what never man had done--to set foot on this place men called the unknown side of the moon. Earth habits were strong: Jerry brought his pistol and a hunting knife out of his pack and hung them at his belt, as the inventor opened the door and sniffed cautiously of the air. Jerry Foster's blood was racing; the air was cold on his face as he rushed out. But it brought to his nostrils odors strange and yet strangely familiar. He was oddly light-headed, irresponsible as a child as he shouted and danced and threw himself high in the air, to laugh childishly at the pure pleasure of his light landing. The sun made long shadows of two ludicrous figures that went leaping and racing across the rocks. Their strength was prodigious, and they were filled with an upwelling joy of living and the combined urge of an eternity of spring-times. The very air tingled with life; there was overpowering intoxication in this potent, exhilarating breath from a world new-born. The ground that they crossed so recklessly was a vast honeycomb of caves. Between the rocks the soil was soft with the waters from melting ice, and the men laughed as they floundered at times in the oozing mud. Beyond was a lake, and it was blue with a depth of color that was almost black, a reflection of the deep, velvet blackness of the sky overhead. And beyond that was the sloping side of an extinct volcano. "Up--up!" Jerry shouted. "From up there we will see the whole world--the whole moon!" He laughed as he repeated the exultant phrase: "The moon--the whole moon!" * * * * * Despite their strength which carried them in wild bounds across impassable chasms, their laboring lungs checked them in the ascent. The joyous inebriation was wearing off. Winslow met his companion's eyes sheepishly as they stopped where a sheer cliff of basalt above caught and held the warmth of the sun's rays. Behind them it rose a straight hundred feet, and before stretched a vast panorama. The sun was mounting now in the sky. It brought into strong relief the welter of volcanic waste that extended in bold detail through the clear air far out to the horizon, where, misty and dim, the first vaporous clouds were forming from the steaming earth. And as they watched, the depressing bareness and emptiness of that gray-black expanse was changing. Far to the east a pink flush was spreading on the hills. It wavered and flowed, and it changed, as they watched, to deep areas of orange and red. The delicate pink swept in waves over valleys and hills, a vast kaleidoscopic coloration that rioted over a strange world. In silence it spilled into the valley below. The slope they had traversed was radiant with color.