Why did the trunk-room have both a radiator and an open fireplace?  Architects were not usually erratic!  It was not fifteen minutes before I was up-stairs, armed with a tape-measure in lieu of a foot-rule, eager to justify Mr. Jamieson’s opinion of my intelligence, and firmly resolved not to tell him of my suspicion until I had more than theory to go on.  The hole in the trunk-room wall still yawned there, between the chimney and the outer wall.  I examined it again, with no new result.  The space between the brick wall and the plaster and lath one, however, had a new significance.  The hole showed only one side of the chimney, and I determined to investigate what lay in the space on the other side of the mantel.

I worked feverishly.  Liddy had gone to the village to market, it being her firm belief that the store people sent short measure unless she watched the scales, and that, since the failure of the Traders’ Bank, we must watch the corners; and I knew that what I wanted to do must be done before she came back.  I had no tools, but after rummaging around I found a pair of garden scissors and a hatchet, and thus armed, I set to work.  The plaster came out easily:  the lathing was more obstinate.  It gave under the blows, only to spring back into place again, and the necessity for caution made it doubly hard.

I had a blister on my palm when at last the hatchet went through and fell with what sounded like the report of a gun to my overstrained nerves.  I sat on a trunk, waiting to hear Liddy fly up the stairs, with the household behind her, like the tail of a comet.  But nothing happened, and with a growing feeling of uncanniness I set to work enlarging the opening.

The result was absolutely nil.  When I could hold a lighted candle in the opening, I saw precisely what I had seen on the other side of the chimney—­a space between the true wall and the false one, possibly seven feet long and about three feet wide.  It was in no sense of the word a secret chamber, and it was evident it had not been disturbed since the house was built.  It was a supreme disappointment.

It had been Mr. Jamieson’s idea that the hidden room, if there was one, would be found somewhere near the circular staircase.  In fact, I knew that he had once investigated the entire length of the clothes chute, hanging to a rope, with this in view.  I was reluctantly about to concede that he had been right, when my eyes fell on the mantel and fireplace.  The latter had evidently never been used:  it was closed with a metal fire front, and only when the front refused to move, and investigation showed that it was not intended to be moved, did my spirits revive.

I hurried into the next room.  Yes, sure enough, there was a similar mantel and fireplace there, similarly closed.  In both rooms the chimney flue extended well out from the wall.  I measured with the tape-line, my hands trembling so that I could scarcely hold it.  They extended two feet and a half into each room, which, with the three feet of space between the two partitions, made eight feet to be accounted for.  Eight feet in one direction and almost seven in the other—­what a chimney it was!