"Well," said Franks taking the fountain pen out of the holder on the desk and beginning to sketch on the blotter, "the course of the _Ariadne_ is not a very crooked one, as courses go. It's a very shallow skew curve. Admitting the worst, collision, we can assume only one thing. If the meteor were small enough to leave the ship in a floating but undirigible condition, it would also be small enough to do nothing to the general direction of the ship. Anything else would make it useless to hunt, follow?" "Yes, go on." "Therefore we may assume that the present position of the ship is within the volume of a cone made by the tangents of the outermost elements of the space curve that is the ship's course. We can take an eight-thousand-mile cylinder out of one place--for the origin of their trouble is between Mars and Terra and the 'shadow' of Terra in the cone will not contain the _Ariadne_." "Might have passed close enough to Terra to throw her right into the 'shadow' of Terra by attraction," objected Arden. "Yeah, you're right. O.K., so we can't take out that cylinder of space. And we add a sort of sidewise cone on to our original cone, a volume through which the ship might have passed after flying close enough to Terra to be deflected. I'll have the slipstick experts give a guess as to the probability of the _Ariadne's_ course, and at the same time we'll suspend all incoming operations. I'm going to set up every kind of detector I can think of, and I don't want anything upsetting them." "What kind of stuff do you expect?" asked Arden. "I dunno. They might have a betatron aboard. In that case we'll eventually get a blast of electrons that'll knock our front teeth out. Don may succeed in tinkering up some sort of electrostatic field. We can check the solar electrostatic field to about seven decimal places right here, and any deviation in the field to the tune of a couple of million electron volts at a distance of a hundred million miles will cause a distortion in the field that we can measure. We'll ply oscillating beams through the area of expectation and hope for an answering reflection, though I do not bank on that. We'll have men on the lookout for everything from smoke signals to helio. Don't worry too much, Arden, your husband is capable of doing something big enough to be heard. He's just the guy to do it." "I know," said Arden soberly. "But I can't help worrying." "Me, too. Well, I'm off to set up detectors. We'll collect something." * * * * * "Have we got anything like a piece of gold leaf?" asked Channing. "I think so, why?" "I want to make an electroscope. That's about the only way I'll know whether we are getting out with this cockeyed electron gun." "How so?" asked Hadley.