"Oof!" came a smothered exclamation from Lents as the ship seemed to pause, to leap forward in space again. The star-studded heavens as seen through the ports were hidden by a curtain of flame, electric blue and as stiff seeming as a steel bar--the trail of the forward rockets. For some minutes there was no sound save the subdued thunder of the hull as it trembled under the tug of the rockets. Then a light flashed redly and a gong sounded. The signal that meant, "fuel half gone." Sine shut off the power, crawled out stiffly. His first glance out of a port showed that they were still falling toward the mysterious cylindrical space wanderer. Kass wiped the sweat from his bald head. "No use wasting any more effort," he said hoarsely. "That thing is a space ship, and there are men in it. The force they have been using on us is some kind of gravity beam--probably it's also their means of space propulsion. They mean to capture us, no doubt----" "And they've reversed the beam!" Lents puffed as he turned away from the ampliscope, pulling his sweat-soaked toga away from his fat body with thumb and forefinger. "We're decelerating fast, but we can't feel it because the force acts on every particle of our bodies exactly the same as on the ship----" "Proving," added Sine, looking out of the port curiously, "that it's a true gravity beam!" The utter stillness of their ship gave the illusion that she was motionless, and that the sinister stranger was drifting toward them. "It _is_ a ship!" Lents rumbled. "Look at her ports. But they're shuttered." "Not a bad idea," Sine agreed. "Protection against pin-point meteorites, anyway." They saw now that the cylinder was slightly rounded at each end, and the end presented to them had at its nose a circular projection, not unlike a very large button, that glowed with a lavender light, which they guessed to be the source of the gravity beam. They were torn between the excitement of discovery and a very natural apprehension. In the dim past, more than 200,000 years ago, there had been a regular commerce between Earth and the Jovian colonies. But the comet swarm, coming out of the mysterious depths of space, had released to the solar system such swarms of meteorites as to make interplanetary travel in the spatial belt between Mars and Jupiter utterly suicidal. It required the passing of two thousand centuries to thin them out sufficiently to permit the voyage of exploration in which these three men were engaged. What would these children of Earth look like after 200,000 years of Jovian evolution? Would they be friendly?