Doctor Wood. Modern Wizard of the Laboratory: The Story of an American Small Boy Who Became the Most Daring and Original Experimental Physicist of Our Day-but Never Grew Up

I told the police that in my opinion, Leroy had taken the rifle apart to find out how the internal mechanism operated. I asked them to find and bring me the rifle if they could. I said it would probably have a brass trigger on it by now all right, since he wouldn’t be fool enough not to put one on when he had a chance. In the meantime I realized that to make a case, we must find out if possible what the steel tubing had originally been made for and where it had come from. It had evidently been a gas-welded tube of commercial factory manufacture. Remembering, in this case, that the Wall Street bomb fragments had never been successfully traced, I decided to take on this search myself. I began by visiting personally a number of big hardware stores and showing them the fragments. They told me the tubing was not standard gauge and must be of foreign make. This did not satisfy me. I next wrote to the editor of Iron Age, the New York metallurgical journal, asking him to send me the addresses of all companies in the United States which manufactured gas-welded steel tubing. He gave me the addresses of seven or eight companies, and I mailed a fragment of the tubing to the first company listed, asking them to send it to the next on the list, and so on until it could be identified. It became a sort of chain letter. The first three companies to which it went could not identify it. But the fourth, the Republic Steel Corporation, replied, “We recognize this tubing as our manufacture. It is a bastard size and is made to order for General Motors to serve as the torque rod of the steering gear of the Chevrolet”. The torque rod runs down the steering post, from the lever which advances and retards the throttle.

* * *

So the tubing in the bomb had definitely come from a Chevrolet garage or storeroom! Dr. Wood was making progress. But there were thousands of Chevrolet garages — hundreds in Maryland and the District of Columbia. It remained to be proven, if possible, that this particular tubing had come from the one garage where Leroy Brady worked. It seemed utterly impossible to do this. But our scientific detective in real life had made an additional microscopic discovery which might point the way.

Wood continues:

I had discovered a tiny, seemingly accidental imperfection, if you could call it that, in the tubing fragments — two parallel scratches, microscopically visible on all the fragments, along the tube’s seam — made probably by a nick on the machine which had polished them. I went to Chevrolet headquarters in Baltimore, first of all, and asked permission to examine the torque rods they had in stock. None of them showed similar scratches along the seams. I then asked Lieutenant Itzel to send someone quietly down to the Chevrolet garage in Washington where Leroy Brady worked, to purchase and bring back a couple of torque rods from the stock there. These were brought to me, and both of them had scratches identical with those on the bomb fragments, showing that they must have come from the same batch of material as the rod used in the construction of the bomb.

The net was closing in. My findings now pointed more and more definitely to Leroy Brady.

I was certain, from the remains of the small copper disk welded by the explosion to the fragment of steel cylinder which had been part of the mechanism, that an old-fashioned percussion cap identical with those used for muzzle-loading shotguns had been used. Furthermore, another fragment of like steel cylinder Lieutenant Itzel had later found showed that a skilled workman had “turned” its end down to exactly the right diameter to fit such a cap.

I felt this might form an additional clue, since muzzle-loading shotguns were extremely rare as late as 1930, even in rural districts. I wasn’t thinking any more about the twenty-two- caliber rabbit rifle which had merely supplied the model for the firing mechanism — but about where the shotgun cap had come from. The cap used in the bomb had been pure copper. I had Itzel buy several boxes of caps, each made by a different arms company, and analyzed the metal. All the types but one were made of brass, copper plated. Only the caps made by Remington were pure copper.

I was now ready to take a chance. I told Lieutenant Itzel to get a search warrant — to search the farm where Herman Brady lived, from attic to cellar, for a muzzle-loading shotgun, or for any evidence that there had been one there, and to look for a box of percussion caps. Three hours later he was back at my laboratory.

“Well, Doc”, he said, “we found the muzzle-loader, and we also found a box of percussion caps on the mantelpiece… and they were Remington!”

I said, “Bring them in, and I think I can promise you the material for an indictment and conviction of one or both of the boys”.