"But what can we _do_ about it?" asked Seaton, exasperated. "We don't want to hang around here twiddling our thumbs for a year waiting for those torpedoes to get to wherever they're going!" "We can do nothing but wait and study. That problem is one of splendid difficulty, as you yourself realize. Its solution may well be a matter of lifetimes instead of years. But what is a year, more or less? You can destroy the Fenachrone eventually, so be content." "But content is just exactly what I'm _not_!" declared Seaton, emphatically. "I want to do it, and do it _now_!" "Perhaps I might volunteer a suggestion," said Caslor, diffidently; and as both Rovol and Seaton looked at him in surprise he went on: "Do not misunderstand me. I do not mean concerning the mathematical problem in discussion, about which I am entirely ignorant. But has it occurred to you that those torpedoes are not intelligent entities, acting upon their own volition and steering themselves as a result of their own ordered mental processes? No, they are mechanisms, in my own province, and I venture to say with the utmost confidence that they are guided to their destinations by streamers of force of some nature, emanating from the vessels upon whose tracks they are." "'Nobody Holme' is right!" exclaimed Seaton, tapping his temple with an admonitory forefinger. "'Sright, ace--I thought maybe I'd quit using my head for nothing but a hatrack now, but I guess that's all it's good for, yet. Thanks a lot for the idea--that gives me something I can get my teeth into, and now that Rovol's got a problem to work on for the next century or so, everybody's happy." "How does that help matters?" asked Crane in wonder. "Of course it is not surprising that no lines of force were visible, but I thought that your detectors screens would have found them if any such guiding beams had been present." "The ordinary bands, if of sufficient power, yes. But there are many possible tracer rays not reactive to a screen such as I was using. It was very light and weak, designed for terrific velocity and for instantaneous automatic arrest when in contact with the enormous forces of a power bar. It wouldn't react at all to the minute energy of the kind of beams they'd be most likely to use for that work. Caslor's certainly right. They're steering their torpedoes with tracer rays of almost infinitesimal power, amplified in the torpedoes themselves--that's the way I'd do it myself. It may take a little while to rig up the apparatus, but we'll get it--and then we'll run those birds ragged--so fast that their ankles'll catch fire--and won't need the fourth-dimensional correction after all." * * * * * When the bell announced the beginning of the following period of labor, Seaton and his co-workers were in the Area of Experiment waiting, and the work was soon under way. "How are you going about this, Dick?" asked Crane.