So Burke went back to the plant and began to make yet another of the peculiarly wound magnets-which-were-not-magnets. This was to have three of the odd-shaped cores, formed in line, of a single piece of Swedish iron. As the windings were put on they'd be imbedded in plastic. Over that would go a casing to keep them from expanding or stretching. It ought to be distinctively different from a magnet. It was an extremely long and utterly tedious job. He knew what he was doing, but he had doubts about the why. As he worked, though, he wrestled out a detailed theory. Discoverers often work like that. It was said that Columbus didn't know where he was going when he started out, didn't know where he was when he got there, and didn't know where he'd been when he got back. The history of the discovery of the triode tube has points of similarity. Burke had begun with a device which destroyed itself when turned on, developed the idea into a device which swelled to uselessness when energized, and now hoped that it would turn out at the third try to be something the textbooks said was impossible. Outside the construction shed, the world went about its business. While Burke worked on through the Sunday noon hour, a Japanese radar telescope aimed at the night sky and made six successive position-findings on the source of the space signals. When sunset found him laboring doggedly at a metal lathe, Croydon made eight. American radar telescopes had made others. Carefully computed, the observations added up to the discovery of an independent motion of the signal source. It moved against the stars as if it were a solar-system body with an orbit in the asteroid belt some three hundred sixty million miles from the sun--as compared to Earth's ninety-two million. At midnight on Sunday, while Burke painstakingly made micrometric examination of the triple magnet-core, Harvard Observatory reported that there should be a very minor asteroid at the spot in space from which the signals came. The coincidental asteroid was known as Schull's object. It was listed as M-387 in the catalogs. It had been discovered in 1913, was a very minor celestial body, had an estimated greatest diameter of less than two miles, and its brightness had been noticed to vary, suggesting that it was of irregular shape. It was too insignificant to have been kept under constant observation, but the signals from space appeared definitely to originate from its position. An hour after midnight, Eastern Standard time, Palomar detected the infinitesimal speck of light which was Schull's object at exactly the place the radar telescopes insisted was the signal source. Satellite-watching stations now monitored the cryptic signals around the clock, and radar telescopes began to sweep space for possible answers to the space broadcast. There was an uncomfortable possibility that the transmitter might not be signaling Earth, after all, but a fellow mystery of space--an associate or a sister-ship.