The sound was not like that of the walking of the human. Nor was it such as an animal would make. It was neither a thud nor a pattering, but more like a scratching shuffle, such as reminded me of nothing that I had ever heard before.

Next moment, however, there came another sort of sound, plainly audible above the footsteps. This was a thin, musical chuckle which ended in a deep, but faint, organ-like throb. It happened only once.

Immediately it was followed by a steady clicking, such as might be made by gently striking a stick against the pavement; only sharper. This lasted a minute, during which the other sounds ceased.

Once more the footsteps. They were not very loud, but in the stillness of that room they all but resounded.

Presently Charlotte could stand it no longer. She placed the ring on the table, where it continued to emit those unplaceable sounds.

“Well! Do—do you people,” stammered Dr. Malloy, “do you people all hear THAT?”

Miss Clarke's face was rather pale. But her mouth was firm. “It is nothing,” said she, with theosophical positiveness. “You must not believe it—it is not the truth of—”

“Pardon me,” interrupted Sir Henry, “but this isn't something to argue about! It is a reality; and the sooner we all admit it, the better. There is a living creature of some kind making that sound!”

“It is the spirit of some two-footed creature,” asserted Mme. Le Fabre, plainly at her ease. She was on familiar ground now. “If only we had a medium!”

Abruptly the sounds left the vicinity of the ring. At first we could not locate their new position. Then Herold declared that they came from under the table; and presently we were all gathered on the floor, listening to those odd little sounds, while the ring remained thirty inches above, on the top of the table!

It may be that the thing, whatever it was, did not care for such a crowd. For shortly the shuffling ceased. And for a while we stared and listened, scarcely breathing, trying to locate the new position.

Finally we went back to our chairs. We had heard nothing further. Nevertheless, we continued to keep silence, with our ears alert for anything more.

“Hush!” whispered Charlotte all of a sudden. “Did you hear that?” And she looked up toward the ceiling.

In a moment I caught the sound. It was exceedingly faint, like the distant thrumming of a zither. Only it was a single note, which did not rise and fall, although there seemed a continual variation in its volume.

Unexpectedly the other sounds came again, down under the table. This time we remained in our seats and simply listened. And presently Sir Henry, referring to the ring, made this suggestion:

“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!”

We all went down except Charlotte, who went upstairs to stay with Ariadne. By turns, each of us held the ring. And as we unlocked the basement door we noted that the invisible, walking creature had reached there before us.

Down the steps went those unseen little feet, jumping from one step to the next just ahead of us all the way. When within three or four steps of the bottom, the creature made one leap do for them all.

I had previously run an extension cord down into the basement, and both compartments could now be lighted by powerful electric lamps. We gave the place a quick examination.

“What's all this newly turned earth mean?” inquired Sir Henry, pointing to the result of Jerome's efforts a few months before. And I explained how he and Harry, on the chance the basement might contain some clue as to the localisation of the Blind Spot, had dug without result in the bluish clay.

Sir Henry picked up the spade, which had never been moved from where Jerome had dropped it. And while I went on to tell about the pool of liquids, which for some unknown reason had not seeped into the soil since forming there, the Englishman proceeded to dig vigorously into the heap I had mentioned.

The rest of us watched him thoughtfully. We remembered that Jerome's digging had been done after Queen's disappearance. And the dog had vanished in the rear room, the one in which Chick and Dr. Holcomb had last been seen. Now, when Jerome had dug the clay from the basement under this, the dining-room, he had thrown it through the once concealed opening in the partition; had thrown the clay, that is, in a small heap under the library. And—after Jerome had done this the phenomena had occurred in the library, not in the dining-room.

“By Jove!” ejaculated General Hume, as I pointed this out. “This may be something more, you know, that mere coincidence!”

Sir Henry said nothing, but continued his spading. He paid attention to nothing save the heap that Jerome had formed. And with each spadeful he bent over and examined the clay very carefully.

Miss Clarke and Mme. Le Fabre both remained very calm about it all. Each from her own viewpoint regarded the work as more or less a waste of time. But I noticed that they did not take their eyes from the spade.

Sir Henry stopped to rest. “Let me,” offered Herold; and went on as the Englishman had done, holding up each spadeful for inspection. And it was thus that we made a strange discovery.

We all saw it at the same time. Embedded in the bluish earth was a small, egg-shaped piece of light-coloured stone. And protruding from its upper surface was a tiny, blood-red pebble, no bigger than a good-sized shot.

Herold thrust the point of his spade under the stone, to lift it up. Whereupon he gave a queer exclamation.

“Well, that's funny!” holding the stone up in front of us. “That little thing's as heavy as—as—it's HEAVIER than lead!”

Sir Henry picked the stone off the spade. Immediately the material crumbled in his hands, as though rotting, so that it left only the small, red pebble intact. Sir Henry weighed this thoughtfully in his palm, then without a word handed it around.

We all wondered at the pebble. It was most astonishingly heavy. As I say, it was no bigger than a fair-sized shot, yet it was vastly heavier.

Afterward we weighed it, upstairs, and found that the trifle weighed over half a pound. Considering its very small bulk, this worked out to be a specific gravity of 192.6 or almost ten times as heavy as the same bulk of pure gold. And gold is heavy.

Inevitably we saw that there must be some connection between this unprecedentedly heavy speck of material and that lighter-than-air gem of mystery. For the time being we were careful to keep the two apart. As for the unexplained footsteps, they were still slightly audible, as the invisible creatures moved around the cellar.

At last we turned to go. I let the others lead the way. Thus I was the last to approach the steps; and it was at that moment that I felt something brush against my foot.

I stooped down. My hands collided with the thing that had touched me. And I found myself clutching—

Something invisible—something which, in that brilliant light, showed absolutely nothing to my eyes. But my hands told me I was grasping a very real thing, as real as my fingers themselves.

I made some sort of incoherent exclamation. The others turned and peered at me.

“What is it?” came Herold's excited voice.

“I don't know!” I gasped. “Come here.”

But Sir Henry was the first to reach me. Next instant he, too, was fingering the tiny, unseen object. And such was his iron nerve and superior self-control, he identified it almost at once.

“By the lord!”—softly. “Why, it's a small bird! Come here.”

Another second and they were all there. I was glad enough of it; for, like a flash, with an unexpectedness that startles me even now as I think of it—

The thing became visible. Right in my grasp, a little fluttering bird came to life.