imaginary moon meant the "Mappa Selenographica," by Beer and Madler. "The moon!" she murmured again. "Yes," remarked Bennie curtly; "the moon--that moon right up there"--he glanced up and wrinkled his forehead--"that _ought_ to be there, I mean! Say, there's something queer about all this! Hard alee, Burke! Steer for the moon!" The aviator pressed his control-lever, and once more the moon floated overhead into their field of vision. But what a moon! Twenty-four times her usual diameter--her circular craters plainly visible to the naked eye, her physical configuration seemingly becoming more and more distinct each moment. "But can we land?" protested the girl, reawakening to the perils of their position. "Suppose we can find no suitable spot--particularly with our machinery out of control? There will be no landing-stage--" "We must land!" he interrupted fiercely. "What's more, we've got to turn the Ring upside down so as to land right side up. It's going to be ticklish business, because we must bring our machine to rest within a hundred miles or so of the lunar surface, and we're traveling more than ten miles a second at the present moment." "But _how_ can you turn the Ring upside down away out here in space?" she expostulated. "By slanting the tractor at its maximum angle," he answered. "Since there is little gravitational force acting on us now, the Ring will then rotate around its center of inertia and bring the moon below us. We can then straighten out the tractor and use its full force to slow down our velocity. As soon as we get within striking-distance of the moon, we will reduce our power and come down by gravitational force." "Have you ever--tried this--turning-maneuver?" she asked hesitatingly. "No; we never have. But we ought to be able to do it--we must do it! Atterbury, throw on your full power; and get ready, Burke, to put her over! Hang on to the ropes, Rhoda, or you may get dizzy! As soon as the tractor starts, we'll get back our weight and have a firm footing again." Rhoda took one last look at the moon blazing out of the darkness of the sky overhead, grasped two of the clothes-lines, and closed her eyes. Again the Ring vibrated to the whir of its propelling engines. Burke threw over the control-lever as far as it would go; the helium ray slanted off until it almost grazed the inner surface of the Ring, and slowly the great machine turned over in space. Bennie, with his face glued to the deadlight in the floor, watched the moon glide gradually into his field of view, and when it was directly beneath them, he shouted to Burke to straighten the tractor. Again the ray swung into the center of the Ring, and they felt the pressure of the floor against their feet.