The air-lock having emptied itself of its contents, Atterbury now released and opened the outer door and lowered a small metal landing-stage, from which hung the steel ladder. Then, with some difficulty, owing to the clumsiness of their new garments, the two men climbed down upon the tufa-like surface of the moon, while Rhoda remained watching them curiously from above. Apart from the puffing-out of the rubber suit, she experienced no new sensations, for she breathed with perfect ease, and the sunlight, falling full upon her body, warmed her through and through. Down below, Atterbury and Burke at first amused themselves by experimenting with the force of lunar gravitation, so much less than that of the earth, and jumped hither and yon--distances of fifteen and twenty feet at a single bound, like mountain-goats leaping from crag to crag. Once having accustomed themselves to their surroundings and their loss of gravity, they climbed up the great tripod and commenced to rig the block and tackle with which they planned to hoist the fresh uranium cylinder to the top of the skeleton tripod and replace their now exhausted supply of fuel. It was clear to Rhoda that this process could conceivably, and in fact probably, have been performed while the Ring was in flight, but she shuddered at the thought of her two friends climbing about on the outside of their machine while in transit at a velocity of twenty miles per second, however imperceptible that velocity might have been. Suppose one of them had fallen? Like the shadow of a lost soul, he would have followed the Ring in its journey among the stars--since, moving at the same speed as the machine through space at the moment of his fall, there would have been nothing to alter his relation to it, and, like a satellite--a true satellite, indeed--he would have flown along beside, or after it, until the tractor was started again and he had been left behind alone in the abyss of space! But here they could quite safely conduct their operations--in fact, as easily as safely--for the uranium cylinder now weighed but one-sixth of what it had weighed upon the earth, and the block and tackle could be handled without difficulty. Leaving the men thus engaged, Rhoda descended the ladder and started off on a walk, feeling her way gingerly along until she could accommodate her muscles to her reduced weight. All about her lay what might have been the ruins of a Selenite civilization metamorphosed by the magic of erosion. Giant monoliths, like pillars, lay tumbled here and there in suggestive juxtaposition with giant blocks of porous stone which might have served as bases for such pillars, as the steps of a lunar temple, or even as an altar to some unknown god.