The house still seemed empty and queer as McGinity and I drove away, around one o'clock, trailing Chief Meigs' car back to the village. The Chief's last act was to station a policeman on guard, which made me a lot easier in my mind.
The situation was still lamentable enough, but McGinity and I, with an air of bravado, continued our inquiries on reaching the village. With police assistance, we had no difficulty in locating the light truck which Orkins had rented, and once located and properly inspected, we found nothing to indicate that it had been used to transport the stolen rocket from the Museum of Science to the East River.
And then McGinity suddenly found something, which was vitally important. A screw from the rocket. Chief Meigs chuckled; he couldn't see that a screw could possibly have any bearing on our situation. When we returned to the police station, I showed him.
"Why, that's just an ordinary screw," he said, after inspecting the screw more closely. "I don't see how it could mean anything."
"No?" I said. "Then you don't know how they make screws on Mars. If you think it's just ordinary, here's a screw-driver and a piece of pine wood. Now, drive it in!"
"That doesn't worry me at all," Meigs bantered. He went to his task cheerfully, even whistling, and giving a wink to several policemen who were looking on. But the screw refused to function in the ordinary way. Finally, he gave it up. "Why the damn thing won't go into the wood is a mystery to me," he remarked, as he handed the screw and screw-driver back to me.
"Because it works in reverse to our screws," I explained, as I drove the screw into the soft wood easily enough by a reverse motion. "There, I've done the job," I concluded, "which proves conclusively that only a Martian screw could be jolted out of a Martian rocket. And as the screw was found in the truck, the van therefore must have carried the rocket."
The Chief of Police grew pop-eyed in amazement.
"Everything about the rocket has this unusual element," I continued, "except the metal from which it was constructed, and it is a scientific fact that the metallic ores which abound on the earth are to be found in other planets."
The Chief's look of blank astonishment prompted me to go on.