Even as they watched it, they could observe its rotation as one can detect the movement of the minute-hand of a clock. The moon had presented no such problem. It was dead, almost without axial motion. But the earth was very much alive, whirling on its axis with a speed at the equator of a thousand miles an hour--nearly that of a shell from a rifled cannon. How could they land upon it? Theirs seemed to be the superhuman task of the clown who tries to climb upon the revolving table at the circus--an impossibility. When they had left the earth, they had assimilated this axial motion, and, in steering their course through the ether, they had allowed for it, as the navigator allows for the tide or the set of the current. But now, on their arrival at the globe's surrounding atmosphere, they would be attempting to land upon a ball revolving with a velocity of ten or fifteen times that of the fastest express-train. "We could land at either of the poles," suggested the research professor. "Of course there wouldn't be any motion _there_!" "Yes; we might do that," agreed Bennie; "or"--and he scratched his head--"we can navigate the Ring toward the earth in a spiral orbit. Anyhow, the Ring has got to follow the earth in her orbit around the sun." "There's something funny about it," interrupted Burke. "Suppose you started at the poles and drove the Ring toward the equator, how would you keep up with the increasing surface-velocity of the earth?" "Why," answered the master of the Ring, "it's the--the--let me see--it must be the atmosphere that would drive you eastward all the time." "Of course!" exclaimed Rhoda. "What a lot of sillies we are! It's perfectly simple. You don't need any spiral orbits or anything else. All you've got to do is to bring the Ring down into the upper atmosphere and hover at a fixed elevation until we are swept along at the full speed of the earth." Burke, who was lighting his pipe, paused and pursed his lips. "Wouldn't we be coming down into a terrific wind?" he inquired. "Fourteen hundred feet a second! My word! Some blow!" "Depends on the latitude, of course," answered Bennie. "We've got to run around the earth as we descend, or else we'll be on the dark side--that is, the _night_ side--when we land. Believe me, I want light for that!" "Quite right!" agreed Atterbury, who had joined the group. "Just look at the earth now, will you?" They all craned their necks to follow his gesture. Through the observation-window, the shining crescent of the globe seemed to fill the whole sky. Burke pressed the control-lever, and they swung leftward, boring through space toward the invisible black wall where the earth's shadow reached out among the stars. Nearer and nearer it drew, then--darkness. Steering by the steady gleam of the friendly planets, as a coasting steamer steers by the distant bead of light that marks the headland, the Ring soared on, bursting at length into full sunlight again.