"Now listen," snapped Channing. "Listen to every word! Mosaic directors are useless. Have you any reason why? It is because of the lag. At planetary distances, light takes an appreciable time to reach your planet. The beam wabbles, swerves out of line because of intervening factors; varying magnetic fields, even the bending of light due to gravitational fields will make the beam swerve microscopically. But, Burbank, a microscopic discrepancy is all that is needed to bust things wide open. You've got to have experienced men to operate the beam controls. Men who can think. Men who can, from experience, reason that this fluctuation will not last, but will swing back in a few seconds, or that this type of swerving will increase in magnitude for a half-hour, maintain the status, and then return, pass through zero and find the same level on the minus side. "Since light and centimeter waves are not exactly alike in performance, a field that will swerve one may not affect the other. Ergo your photomosaic is useless. The photoelectric mosaic is a brilliant gadget for keeping a plane in a spotlight or for aiming a sixteen-inch gun, but it is worthless for anything over a couple of million miles. "So I've called the men back to their stations. And don't try anything foolish again without consulting the men who are paid to think!" Channing got up and left. As he strode down the stairs to the apartment level, he met many of the men who had been laid off. None of them said a word, but all of them wore bright, knowing smiles. * * * * * Monday morning! Burbank was himself again. The rebuff given him by Don Channing had worn off and he was sparkling with ideas. He speared Franks with the glitter in his eye and said: "If our beams are always on the center, why is it necessary to use multiplex-diversity?" Franks smiled. "You're mistaken," he told Burbank. "They're not always on the button. They vary. Therefore we use diversity transmission so that if one beam fails momentarily, one of the other beams will bring the signal in. It is analogous to tying five or six ropes onto a hoisted stone. If one breaks, you have the others." "You have them running all the time, then?" "Certainly. At several minutes of time-lag in transmission, to try and establish a beam failure of a few seconds' duration is utter foolishness." "And you disperse the beam to a thousand miles wide to keep the beam centered at any variation?" Burbank shot at Channing. "Not for any variation. Make that any _normal_ gyration and I'll buy it." "Then why don't we disperse the beam to two or three thousand miles and do away with diversity transmission?" asked Burbank triumphantly.