They met, immediately whisked into the sky and back to more than a safe distance. Then they went to work, searching etheric space and subetheric space for radiations. They hurled megawatt pulses of radio energy and subradio energy at the ticking thing. They thundered at it with audio, covering all known manner of vibration from a few cycles per minute of varying pressure to several megacycles of sheer air-wave. They mixed radio and audio, modulated the radio with the audio and hurled both continuous waves and pulsed waves, and mixed complex combinations of both. Then they modulated the subradio with radio, which was modulated with audio and they bombarded it with that. Rejecting the radiation bands entirely, they went after it, exploring the quasi-optical region just below the infra-red in the same complete manner. They fired at it constantly, climbing up into the heat waves, up into visible light and out into the ultra-violet. They hurled Brentz rays, Roentgen rays, and hard X. They tuned up the betatron and lambasted it with the most brittle of hard X rays. They hurled explosive charges at it, to shock it. Then they sent drone fliers, radio controlled, and waved reflecting masses at it gently and harshly by flying the drones back and forth above it. After three hours of this--and three more incoming robombs of the same type had been reported, they gave up. "They're piling up," grunted Lindsay. "Wish we could move it," said Grant. "You always wish that. You tell us how to grapple with three hundred tons of glass-slick, super-hard ovoid with a high diamagnetic surface and a built-in radiation shield. Moving them is the easiest answer--and the one initially avoided." Harris blinked. "Nothing else?" "There's nothing left but to go out and pull its teeth," said Lindsay. "Nothing we know can detonate the thing." Harris smiled knowingly. "Naturally," he said. "Their point in life is to immobilize Terra. They must not go off until they are ready. They're willing to wait. They found out we could detonate them and then return to work in a couple of hours with radiation shields. So they now get a fuse that cannot be extracted and cannot be detonated until they want it to. Give 'em one chance to prove one effective, and all Terra will be immobilized by them, and they'll drop everywhere. Also, maintaining the force fields takes a lot of valuable power. And if we shut off the fields, it might go up and then we'd lose the whole place." "How I wish we could take pictures." "Photographs?" asked Grant, smiling. "I saw one of them once. A family heirloom. Too bad, of course. But what do you expect when the whole world is living in a sort of bath of neutrons, and silver itself becomes slightly radioactive? After all, photography used to use a silver compound of some sort if my physical history is right."