More data turned up. M.I.T. made examination of the signals themselves. Timed, the intervals between notes varied as if keyed by something alive. But successive broadcasts were identical to microseconds. The conclusion was that the original broadcast had been set up by hand, as it were, but that all were now transmitted mechanically--automatically--by a robot transmitter. It was Monday morning when Burke completed the last turn of the last winding of his three-element pseudo-magnet. There are many things which become something else when they change in degree. Electromagnetic radiation may be long radio waves or radiant heat or yellow light or ultraviolet or X-rays, or who knows what, according to its frequency. It is different things with different properties at different wavelengths. Burke believed that his cores and windings were something other than magnets because the "flux" they produced was of a different intensity. He did not believe it to be magnetism. At nine o'clock Monday morning, he was clumsy from pure, weariness when he began to fit the outer case on the thing he'd worked so long to complete. The hand-weapon in his dream undoubtedly flung bullets through a rifled bore penetrating the very center of the multiple core. The design of the hand-weapon ruled out any possibility of a considerable recoil. It wasn't built to allow the hand to take a recoil. So there must be no recoil. On that basis, Burke had made what finally amounted to a thick rod some six inches long and two in diameter. With the casing in place, it was absolutely solid. There was no play for the windings to expand into. He blinked at it. Common sense said he ought to put it aside and test it when his mind was not nearly numb from fatigue. Then Sandy came into the constructions shed, looking for him. She'd arrived for work and seen his car outside the shed. Her expression indicated several things: a certain uneasiness, and some embarrassment, and more than a little indignation. When she saw him unshaven and wobbly with weariness, she protested. "Joe! You've been working since Heaven knows when!" "Since I left you," he admitted. "I got interested." "You look dreadful!" "Maybe I'll look worse after I try out this thing I've made. I'm not sure." "When did you eat last?" she demanded. "And when did you sleep?" He shrugged tiredly, regarding the thing in his hands. He'd had enough experience contriving new things to know that no theory is right until something that depends on it has been made and works. He tended to be pessimistic. But this time he thought he had it. "Is this working night and day a part of your reaction to those signals?" asked Sandy unhappily. "If it is--"