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Among the children's possessions there was a coil of thread-fine copper wire. Somebody had snipped off a bit of it for test, and discovered that the wire was superconductive. A superconductor is a material which has no electrical resistance whatever.
In current Earth science tin and mercury and a few alloys could be made into superconductors by being cooled below 18° Kelvin, or four hundred odd degrees Fahrenheit below zero. Above that temperature, superconductivity did not exist. But the children's wire was a superconductor at room temperature. A thread the size of a cobweb could carry all the current turned out by Niagara without heating up.
We can't have superconductors above 18° Kelvin, which is colder than liquid hydrogen. But a superconductor acts like a magnetic shield, no, not exactly. But you can't touch a magnet to one. Induced currents in the superconductor fight its approach. I'd like to know what happens to the magnetic field. Does it cancel, or bounce, or what? Could it, for instance, be focussed?" "I don't see ..."
And he was fascinated by the innumerable possibilities the technology of the children's race suggested. He yearned for a few days alone with some low-temperature apparatus. The hand-tool of Fran's bothered him. He told Gail. "What has low temperature to do?" she asked. "They've got some wire that's a superconductor at room temperature.
"Neither do I," said Soames. "But I've got a hunch that the little pocket gadget Fran carries has some superconductor in it. I think I could make something that wouldn't be his instrument, at all it would do different things but that gadget does suggest some possibilities I fairly ache to try out." "And I," said Gail, with a faint smile, "I want to try to write something that nobody would print.
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