Silence. Then more sternness. But ultimately the official voice said, "I'll get a code expert on this." Burke handed the microphone to Sandy. "Take over. We've got to arrange a cipher so nobody who listens in can learn about official business. We may use a social security number for a key, or the name of your maiden aunt's first sweetheart, or something we know and Washington can find out but that nobody else can. Hm. Your last year's car-license number might be a starter. They can seal up the records on that!" Sandy took over the job. What was transmitted to Earth, of course, could be picked up anywhere over an entire hemisphere. Somebody would assuredly pass on what they overheard to, say, nations the United States would rather have behind it than ahead of it in space-travel equipment. Burke's suggestion of a cipher and instructions changed his entire status with authority. They'd rather have had him come back, but this was second best, and they took it. From Burke's standpoint it was the only thing to do. He had no official standing to lend weight to his claim that lunatic magnet-cores with insanely complicated windings would amount to space-drive units. If he returned, in the nature of things there would be a long delay before mere facts could overcome theoreticians' convictions. But now he was forty-five thousand miles out from Earth. He had changed course to home on the beeping signals from M-387, was accelerating at one full gravity and had been doing so for forty-five minutes. And the small ship already had a velocity of twenty miles per second and was still going up. All the rockets that men had made, plus the Russian manned-probe drifting outward now, had become as much outdated for space travel as flint arrowheads are for war. Burke returned to the microphone when Sandy left it to get a pencil and paper. "By the way," he said briskly. "We can keep on accelerating indefinitely at one gravity. We've got radars. We got them from--" He named the supplier. "Now we want advice on how fast we can risk traveling before we'll be going too fast to dodge meteors or whatnot that the radar may detect. Get that figured out for us, will you?" He gave back the instrument to Sandy and returned to his inspection of every item of functioning equipment in the ship. He found one or two trivial things to be bettered. The small craft went on in a singularly matter-of-fact fashion. If it had been a bomb shelter buried in the pit beside the mould in which it was built, there would have been very little difference in the feel of things. The constant acceleration substituted perfectly for gravity. The six television screens, to be sure, pictured incredible things outside, but television screens often picture incredible things. The wall-gardens looked green and flourishing. The pumps were noiseless. There were no moving parts in the drive. The gyro held everything steady. There was no vibration.