“Not exactly,” Frescura replied. “I’ve mentioned the theory before. But the application is new.” Talbot was relieved. He wouldn’t be expected to know much about it. “Go over it for my benefit,” he urged. “Quite a bit has happened in the interval.” Frescura glanced at him queerly, and he regretted having made the request. “You ought to remember this,” said the scientist. “Well, it’s off the mainline of our experiments, but I thought we might get some constructive results. We make the tube of dissimilar metals, one jacketing the other. When it is heated we get a thermocouple effect. An electric charge is generated. The charge on the inside of the tube repels the exhaust molecules so that they don’t actually come in contact with the inside surface. This reduces both heating and erosion.” Talbot rubbed his head. “I remember. Is it ready to go?” “It is,” said Frescura grimly. “But don’t stand there unless you want another accident.” Talbot got out of the way hastily. He was blundering in practically every statement he made. There was far more to a person than personality, or his outward appearance. In Talbot’s particular case knowledge was lacking--not textbook information, but intimate details that could be acquired only by working closely with the man he was impersonating. So far it hadn’t been serious. But he’d have to watch himself. Frescura moved a switch, and there was a rumble within the enclosure. A tiny, barely visible flame shot out a foot from where Talbot had been standing. The rumble rose to a shriek, and quickly passed beyond the range of hearing. The flame disappeared, but Talbot could still feel the heat. Frescura picked up a wrench and tossed it into the path of the exhaust. The instrument vanished and the huge curved backstop a hundred feet away was suddenly coated with a thin film of molten metal. Frescura grinned at him. “You’ve got to watch these things,” he said. He peered into an eyepiece on the enclosure, making several adjustments before he seemed satisfied. “Take a look,” he said to Talbot. Talbot looked, his eyes gradually growing accustomed to the intense light that passed through the dense filters. He could see the inside of the rocket tube, and the fierce incandescence shooting by. Actually none of the exhaust gasses touched the walls of the tube, for there was a static area an inch in thickness next to the wall where nothing seemed to penetrate. As he tried to see more clearly exactly what was happening the enclosure began to vibrate again, shaking the foundation. But the metal held. The shriek declined to a rumble and then the sound died away completely. Talbot blinked and straightened up. Frescura was jotting down readings from the instruments on the enclosure. He made a few quick calculations. “The test corresponds to a rocket speed of thirty thousand miles a second,” he said.