"I can make out nothing through those cloud-belts," he said. "Those belts show, as astronomers have always believed, that Neptune has a great atmosphere. But what lies beneath them we'll not know until we penetrate through them to the planet's surface." "That won't be long," I told him. "We're already only fifty million miles from Neptune--should reach it in seven or eight hours more." "You'll be slowing the flier's speed before long then?" asked Whitely, and I nodded. "We'll wait until we're ten million miles from it and then cut out our rear-ray that's pushing us on, and send out a front force-ray toward Neptune to break our progress." Those next several hours, however, seemed to us in passing to be drawn out to infinite length, so great had become our suspense. At last, however, as we stared tensely ahead, Randall gave the word beside me that marked our place as within ten million miles of the great planet, which had now grown to a vast pale-green cloudy disk in the heavens before us. And as he gave that word I snapped shut one of the six switches before me, turning off the great rear force-ray of the flier, and at the same moment snapped open another switch that sent a great force-ray stabbing straight out from the ray-opening in the flier's front, stabbing straight out toward the great disk of Neptune ahead! Almost at once our mad flight toward that huge world began to diminish in speed. Minute by minute the figures on the speed-dial crept backward, so that from eight million miles an hour our speed dropped quickly to six million, and then to four and to three and to two million. With this swift decreasing of our speed we were experiencing now the reverse of that pressure that had been ours upon our acceleration, since now we were straining upward and forward against the straps of our chairs, the pneumatic shock-absorbing apparatus of those chairs functioning now as it had done then. But though we felt again the dizziness and slight nausea attendant upon these tremendous changes of speed, we forgot that in our intent contemplation of the huge world that loomed but a million miles ahead, its tremendous pale-green sphere, belted with great cloud-masses, seeming to fill the heavens before us. Already Marlin, with his instruments, had found as we neared Neptune that the giant world's rotatory speed was a little more than twenty Earth-hours, solving a problem that long had defied Earth's astronomers by the discovery that the great planet turned on its axis each score of hours.