Marlin approved the suggestion, so after sending the flier out farther from Saturn and ahead of it by oblique applications of the side-ray, we held it carefully in space until it was headed toward the far green spot of Neptune, and then turned on the rear force-ray with half its full power at the start. At once, with terrific acceleration, we were flashing on toward Neptune, the giant power of the ray pushing against Saturn and driving our flier ever outward. So tremendous was that acceleration, indeed, that despite the shock-absorbing apparatus of our chairs we came near to being overcome by the awful pressure upon us. Yet it was necessary that we use the highest possible speed and acceleration, now, for our former speed and acceleration had been completely lost when the halting of the generators had allowed Saturn to pull us inward. And though we were now flashing out past Saturn's orbit, with only the orbit of Uranus between us and our goal of Neptune, we had still two-thirds of our journey before us! So colossal are the distances between the great outer planets, distances beside which the gaps between Mars and Earth and Venus and Mercury seem tiny.
With the utmost acceleration of speed that we could stand, though, our space-flier was now hurtling outward, its great force-ray pushing against Saturn with more and more power and sending us flashing forward with greater and greater velocity. In the next dozen hours of our flight we had reached again to the speed of five million miles an hour that had been ours before we had met with our misadventure at Saturn. And as we hurtled on Neptune was slowly largening before our eyes, its distant, tiny little spot of calm green light becoming bigger, brighter, though very slowly. But the eyes of Marlin and Whitely and Randall and myself were always upon that green light-spot as we hurtled on, hour following hour and day following day in our eventless onward flight through the solar system's outer immensities of space. And still our speed was steadily growing until at last, by the time we approached Uranus' orbit, we were flying through the great void at the space-flier's utmost velocity, more than eight million miles an hour.
That was a speed colossal, yet so accustomed had we four become to the space-flier's tremendous velocities that it seemed not unusual to us. Flashing through the void as we were, the only objects by which one could measure speed were the planets before and behind us, and these changed in size so slowly as to make our speed seem small. The greatest change to us in the attaining of the space-flier's immense utmost speed was the change of conditions inside the flier itself. Formerly the pressure of our constant acceleration had replaced to some degree the effects of gravitation, that pressure forcing us always towards the flier's rear, as we turned more and more power into our giant pushing ray, as we shot out with greater and greater speed. But now, with our utmost speed attained and that acceleration's pressure missing, we floated inside the flier as though entirely weightless, being attracted only very slightly toward the walls by the slight gravitational attraction of the flier's mass itself. So that now the straps across chairs and bunks and the handholds here and there on the walls that we had provided proved indispensable to us, indeed.
It was upon the fifteenth day after our start from Earth, the first day of July as I noted by Earth-reckoning, that we crossed the orbit of Uranus. As we approached that orbit, only our recording distance-dials, of course, marking the fact that we were nearing the path of Uranus, I stood or rather floated with Marlin and Whitely at the flier's rear windows, gazing backward. Behind us gleamed in the star-swept heavens the planets past which we had come, and those others beyond them. Great Saturn with his vast rings that had almost been our deaths was already dwindling fast, as our flier shot out from it with its force-ray pressing with ceaseless power against it. Already the huge ringed planet was but a tiny yellow disk of light to our eyes, so far out from it we were.
To the left, too, shone the white star of giant Jupiter, small but intensely brilliant still, while farther distant and infinitely fainter was the red spark that was Mars. Our eyes shifted from these to the bluish light-point that was Earth, and then beyond it to the little disk of brilliant fire that was the sun, its light and heat reaching us now in the smallest of quantities as we fled on into the chill immensities of the outer reaches of the solar system. There close beside that fiery little sun-disk we could also make out the silvery little light-point that was Venus, and by making use of a small hand-glass could also discern closer even beside the sun the tiny point of rosy light that we knew to be Mercury, smallest and inmost of all the planets. But as we watched there, as our space-flier hurtled on at unvarying, colossal speed over the orbit of Uranus, it was toward Uranus itself we were gazing. Far back from us on the solar system's other side hung the green spot of light that was Uranus, booming onward in its vast path around the sun, but though we watched steadily through the hand-glass toward it we were unable to make out the four small moons that accompany the great green planet, which shone with a deeper green even than the greenish spot of Neptune, ahead.
"Uranus—Venus—Mercury——," said Marlin, as he gazed musingly backward. "Those three we have not passed, yet they're no greater mysteries to us than those that we have passed. But some day——"
"Some day——," I repeated, staring back, lost in thought myself, not completing, any more than Marlin, the thought that I had started to express.
Nor did I need to complete it, for as Marlin and Whitely and I stared back to where the sun's disk sent its light bravely out across the unthinkable reaches of space that separated us from it, our thoughts were all on those three planets, on Uranus and Venus and Mercury, and on those others, Mars and Jupiter and Saturn, that we had passed. What wonders, unknown to us, might not exist upon any of those worlds? But they were wonders barred to us for the time, since time was the one thing of which we had the least, in our great rush outward to the sun's outermost planet, in our desperate race outward to attempt to save our own Earth from the doom that hovered over it. For still that doom cast its shadowing wing darkly over Earth, still Whitely's instruments informed us that the giant force-ray from Neptune was stabbing back toward the sun, turning the sun ever faster at the same remorseless rate. So that it was toward Neptune, after minutes, that we turned, taking our places in our chairs beside Randall, at the controls, and gazing with him toward the planet far ahead that was our goal.
And now that we had crossed the orbit of Uranus, some two-thirds of our colossal journey's length lay behind us, and Neptune was becoming ever brighter ahead, its pale-green spot of light having become almost as brilliant to our eyes as Saturn, behind us. As we viewed it through our telescope, too, we could make out the tiny light-point of Triton, the single moon of Neptune. Somewhat larger than our own moon was Triton, we knew, and we could see through our glass what had long been known by Earth's astronomers, that this single moon of Neptune's revolved about it in a plane sharply slanted or inclined to the plane of Neptune's equator, to the general plane of the ecliptic or solar system. And close indeed seemed the light-point of this single moon to Neptune, since we knew that it was at almost the same distance from the great planet as our own moon is from Earth.