The loose body I now saw to be a cylinder of lead about half an inch long, accurately fitting the inside of the cylinder but capable of slipping freely backwards and forwards.
The steel point which I had noticed in the hole at the apex of the conical end, was now seen to be the pointed termination of a slender steel rod which projected fully an inch into the cavity of the cylinder, and the conical end itself was a solid mass of lead.
"Well ?" queried Thorndyke, seeing that I was still silent.
"You tell me it is not an explosive bullet," I replied, "otherwise I should have been confirmed in that opinion.

I should have said that the percussion cap was carried by this lead plunger and struck on the end of that steel rod when the flight of the bullet was suddenly arrested." "Very good indeed," said Thorndyke.

"You are right so far that this is, in fact, the mechanism of a percussion shell.
"But look at this.

You see this little rod was driven inside the bullet when the latter struck the wall.

Let us replace it in its original position." He laid the end of a small flat file against the end of the rod and pressed it firmly, when the rod slid through the hole until it projected an inch beyond the apex of the cone.