Presently, after a warning gesture, he set the rocket timer and pressed the firing button. All the ghastly impact of high acceleration repeated itself. But, lasting only two seconds, it was not much worse than--say--falling from a second-story window down on a hard mattress. It lasted longer, but there was not much other difference. It did not build up to the torture of continued rocket thrust. Then the ship floated on. There was utter silence. The vertical-slot altimeter indicated a height which seemed absolutely steady. The Doppler-effect velocity meter gave a reasonably satisfactory if not too precise message. McCauley was working intensively on his course when Furness said, with an effort: "Ground says satellite-watching stations picking up our signal report a good course. It could be a little more to the south." McCauley flipped on his own microphone-to-ground switch. "I figure I'm still a little short on velocity," he said crisply. "I'll have to blast again for about a second. Figure me an angle of heading for ten minutes from now, for a one-second blast. I'll report my figures for checking." He did not bother with the ship controls now, of course. The ship was in orbit, like the numerous satellites circling Earth west to east and north and south. It did not matter which way it pointed. There was no air to impede its progress. As a matter of fact, a trace of rotating motion had been produced by a slight off-centering of the rocket thrust. The ship's center of mass had changed slightly because of fuel consumption. There was silence. McCauley worked on busily. From time to time Furness spoke as if with great effort. He relayed the altitude from the slot radar. He relayed the velocity from the Doppler gauge. He relayed hull temperature, cosmic frequency, ultraviolet intensity. He did not report any physical sensations, but once he spoke as if in answer to a question: "It must be out of order if it says that." He might be referring to the telemetering apparatus which relayed the pulse and respiration and blood pressure readings of the two men in the ship. In eight minutes McCauley reported the bearing he considered the ship should point to so that a one-second rocket thrust, adding its effect to all previous courses and speeds--plus a correction for the diminished weight of fuel in the tanks--would produce an exactly perfect orbit for the ship. Furness repeated it while McCauley took more horizon-to-star observations to check the present line of motion. "Ground checks your figures," said Furness. "They say congratulations on perfect astrogation under service conditions. It's right." "Okay," McCauley said absently.