I looked up at Sir John, and he gave me a satisfied nod as he tried one of the seals, and then we both stood as if turned to stone, for from just at my feet there came a dull knocking sound, and as I looked down, I could see the black sawdust shake. What I wanted to do was to run, for I felt that the place was haunted; but I couldn't move, and when I looked at Sir John, he was holding up his right hand, as if to order me to be silent. Then he held his candle down, for there was another sound, but this time more of a grinding cracking in a dull sort of way, just as if some one was forcing an iron chisel in between the joints of the stones. Then there was a long pause, and I half thought it had been fancy; but soon after, as I stood there hardly able to breathe, the sawdust just in one place was heaved up about an inch. I was terribly alarmed, not knowing what to think; but Sir John was brave as brave, and he signed to me not to speak, and stood watching till there was a dull cracking sound, the sawdust was heaved up again, and all at once I seemed to get a hot puff of that burnt oily smell right in my nose. Then I began to understand, and felt afraid in a different fashion, as I knew that we had only got there just in time. The next minute Sir John made a movement toward me, took my candle and turned it upside down, so that it went out, and then pointed back toward the outer cellar, as he put his lips to my ear: "Iron bar!" I stepped back softly, and got the iron bar from where it lay on the edge of a bin, and I was about to pick up the screw-driver, when I remembered where the wooden mallet lay, and I picked up that before stepping softly back to where Sir John was watching the floor; and now I could see that the sawdust was higher in one place, as if a flagstone had been heaved up a little at one end. There was no doubt about it, for, as I handed the crowbar, the end of the stone was wrenched up a little higher and then stuck; for it was tightly held by those on either side; but it was up far enough to let a thin ray of dull light come up through the floor and shine on the side of one of the old chests. It was a curious scene there, in that gloomy cellar: Sir John standing on one side, candle in his left, the iron bar in his right hand, and me on the other bending down ready with the mallet to hit over the head the first that should come up through the floor. For, though horribly alarmed, I could understand now what it all meant--an attempt to steal the gold in the chests, though how those who were working below had managed to get there was more than I could have said. As we watched, the smell of the burnt oil came through, and I knew that it must have been going on for a long time.