“Suppose we seal it up, and see whether it inducts the sound then as well as when exposed.”
This appealed to Herold very strongly; the others were agreeable; so I ran upstairs to my room and secured a small screw-top metal canister, which I knew to be airtight. It was necessary to remove the stone from the ring, in order to get it into the opening in the can. Presently this was done; and while our invisible visitor continued his scratchy little walking as before, I screwed the top of the can down as tightly as I could.
Instantly the footsteps halted.
I unscrewed the top a trifle. As instantly the stepping was resumed.
“Ah!” cried Herold. “It's a question of radioactivity, then! Remember Le Bon's experiments, Sir Henry?”
But Miss Clarke was sorely mystified by this simple matter, and herself repeated the experiments. Equally puzzled was Mme. Le Fabre. According to her theory, a spirit wouldn't mind a little thing like a metal box. Of them all, Dr. Malloy was the least disturbed; so decidedly so that General Hume eyed him quizzically.
“Fine bunch of hallucinations, doctor.”
“Almost commonplace,” retorted Malloy.
Presently I mentioned that the Rhamda had come from the basement on the night that Ariadne had materialised; and I showed that the only possible route into the cellar was through the locked door in the breakfast room, since the windows were all too small, and there was no other door. Query: How had the Rhamda got there? Immediately they all became alert. As Herold said:
“One thing or the other is true; either there is something downstairs which has escaped you, Fenton, or else Avec is able to materialise in any place he chooses. Let's look!”