"That's a thought. Johannson, have one of your men run around and remove all lights that aren't absolutely necessary. He can kill about three-quarters of them, I'm certain. That'll save us a few kilowatt hours," said Channing. "And another thing. I'm about to drop the power of our electron gun and run it continuously. If the boys are anywhere in the neighborhood, they'll be needing continuous disturbance for direction finding. I'd say in another five hours that we should start continuous radiation." "You know, Channing, if this thing works out all right, it will be a definite vote for pure, deductive reasoning." "I know. But the deductive reasoning is not too pure. It isn't guesswork. There are two factors of known quality. One is that I know Walt Franks and the other is that he knows me. The rest is a simple matter of the boys on the station knowing space to the last inch, and applying the theory of probabilities to it. We'll hear from them soon, or I'll miss my guess. Just you wait." "Yeah," drawled Captain Johannson, "we'll wait!" * * * * * Chuck Thomas made another computation and said: "Well, Walt, we've been narrowing them down for quite a long time now. We're getting closer and closer to them, according to the field intensity. I've just got a good idea of direction on that last five minute shot. Have Franklen swivel us around on this course; pretty soon we'll be right in the middle of their shots." "We're approaching them asymptotically," observed Walt. "I wish I knew what our velocity was with respect to theirs. Something tells me that it would be much simpler if I knew." "Walt," asked Arden, "how close can you see a spaceship?" "You mean how far? Well, I don't know that it has ever been tried and recorded. But we can figure it out easy enough by analogy. A period is about thirty-thousandths of an inch in diameter, and visible from a distance of thirty inches. I mean visible with no doubt about its being there. That's a thousand to one. Now, the _Ariadne_ is about six hundred feet tall and about four hundred feet in its major diameter, so we can assume a little more than the four hundred feet--say five hundred feet average of circular area, say--follow me?" "Go on, you're vague, but normal." "Then at a thousand to one, that becomes five hundred thousand feet, and dividing by five thousand--round figures because it isn't important enough to use that two hundred and eighty feet over the five thousand--gives us one thousand miles. We should be able to see the _Ariadne_ from a distance of a thousand miles." "Then at four thousand miles per second we'll be in and through and out of visual range in a half second?" "Oh, no. They're rambling on a quite similar course at an unknown but high velocity. Our velocity with respect to theirs is what will determine how long they're within visual range."