When they had resumed their ordinary clothing the _Astronef_ rose from the surface of the plain, crossed the encircling wall at the height of a few hundred feet, and made her way at a speed of about fifty miles an hour towards the regions of the South Pole. Behind them to the north-west they could see from their elevation of nearly thirty thousand feet the vast expanse of the Sea of Clouds. Dotted here and there were the shining points and ridges of light marking the peaks and crater-walls which the rays of the rising sun had already touched. Before them and to the right and left rose a vast maze of ragged, splintery peaks and huge ramparts of mountain-walls enclosing plains so far below their summits that the light of neither sun nor earth ever reached them. By directing the force exerted by what might now be called the propelling part of the engines against the mountain masses which they crossed to right and left and behind, Redgrave was able to take a zigzag course that carried them over many of the walled plains which were wholly or partially lit up by the sun, and in nearly all of the deepest their telescopes revealed something like what they had found within the crater of Tycho. At length, pointing to a gigantic circle of white light fringing an abyss of utter darkness, he said: "There is Newton, the greatest mystery of the moon. Those inner walls are twenty-four thousand feet high; that means that the bottom, which has never been seen by human eyes, is about five thousand feet below the surface of the moon. What do you say, dear--shall we go down and see if the searchlight will show us anything? You know there may be something like breathable air down there, and perhaps living creatures who can breathe it." "Certainly!" replied Zaidie decisively; "haven't we come to see things that nobody else has ever seen?" Redgrave went down to the engine-room, and presently the _Astronef_ changed her course, and in a few minutes was hanging with her polished hull bathed in sunlight, like a star suspended over the unfathomable gulf of darkness below. As they sank below the level of the sun-rays, Murgatroyd turned on both the searchlights. They dropped down ever slowly and more slowly until gradually the two long, thin streams of light began to spread themselves out; the lower they went the more the beams spread out, and by the time the _Astronef_ came gently to a rest they were swinging round her in broad fans of diffused light over a dark, marshy surface, with scattered patches of grey moss and reeds, with dull gleams of stagnant water showing between them. "Air and water at last! I thought so," said Redgrave, as he rejoined her on the upper deck; "air and water and eternal darkness! Well, we shall find life on the moon here if anywhere." "I suppose we had better put on our breathing-dresses, hadn't we?" asked Zaidie.