"Decidedly not. We want to trace them, without exciting any more suspicion than is absolutely necessary. How often, would you say, do they have to come here to service this station—change tapes, and whatever else might be necessary?"
"Change tapes, is all. Not very often, by the size of those reels. If they know the relative motions exactly enough, they could compute as far ahead as they care to. I've been timing that reel—it's got pretty close to three months left on it."
"And more than that much has been used. It's no wonder we didn't see anything." Samms straightened up and stared out across the frightful waste. "Look there—I thought I saw something move—it is moving!"
"There's something moving closer than that, and it's really funny." Jack laughed deeply. "It's like the paddle-wheels, shaft and all, of an old-fashioned river steam-boat, rolling along as unconcernedly as you please. He won't miss me by over four feet, but he isn't swerving a hair. I think I'll block him off, just to see what he does."
"Be careful, Jack!" Samms cautioned, sharply. "Don't touch it—it may be charged, or worse."
Jack took the metal cover, which he was still holding, and by working it back and forth edgewise in the sand, made of it a vertical barrier squarely across the thing's path. The traveler paid no attention, did not alter its steady pace of a couple of miles per hour. It measured about twelve inches long over all; its paddle-wheel-like extremities were perhaps two inches wide and three inches in diameter.
"Do you think it's actually alive, sir? In a place like this?"
"I'm sure of it. Watch carefully."
It struck the barrier and stopped. That is, its forward motion stopped, but its rolling did not. Its rate of revolution did not change; it either did not know or did not care that its drivers were slipping on the smooth, hard sand; that it could not climb the vertical metal plate; that it was not getting anywhere.
"What a brain!" Northrop chortled, squatting down closer. "Why doesn't it back up or turn around? It may be alive, but it certainly isn't very bright."