Peter looked into the water. “Not deep,” he remarked. He pulled off his shoes and socks, hitched up his trousers, and waded in. “Don’t move round too quickly,” called Anthony. “It won’t be healthy for bare toes when you do find it.” Peter trudged round treading the mud at the bottom with the utmost respect. Step by step he circled the water-pool—then suddenly Bathurst saw him bend down. When he straightened himself he held a longish piece of stone just as had been described to him. One end resembled the neck of a bottle and it broadened out towards its other end to a width of about seven inches. This end had sharp jagged edges. Anthony took it from Peter’s outstretched hand. “As I thought, Daventry,” he declared, as Peter made the path again, “a short time ago this piece of stone formed part of the path that we are now standing upon—you know what it is of course?” Peter replied very promptly. “I’ve a very shrewd idea,” he declared. “I’m just beginning to see daylight—your theory is that that piece of jagged stone——” “Was used to kill Laurence Stewart,” said Anthony, “and then thrown into that pool—and it’s more than a theory—it’s a fact.” CHAPTER XVI Mr. Bathurst Again Samples the Bookcase Peter whistled. “You seem pretty sure of it. But all the same——” Anthony interrupted him a trifle impatiently. “Those little mud pellets and small stones told me an unmistakable story. It seemed to me a most important factor in the case—remember no weapon was found near the body. It was obvious that Stewart had been struck from behind—I immediately deduced a sharp and heavy piece of stone. But if it hadn’t been for the proximity of the ink-bowl to the dead man’s head, the true significance would probably have escaped me. For the wound on the head was clean—I inquired of the doctor through Goodall. The murderer held the piece of stone by the ‘neck’ end—soil side uppermost—and struck Stewart with the comparatively clean part, and the force of the blows caused the small stones underneath (as they lay originally) to be dislodged.” He held out the weapon to Daventry. “Of course the water in the pool has cleaned it, but I daresay a thorough and scientific examination may yield us some little evidences to support my theory. Time will tell—we’ll take it back to the library and hand it over to Goodall upon his return from London, as a souvenir.” He turned to Peter. “But not a word till I say when.” Back in the library, Anthony got to work again very quickly. “Stay here a moment, Daventry,” he said, “while I have a word with young Stewart—I won’t keep you waiting long—put this in a safe place”—he handed over the recent discovery. A matter of ten minutes saw him back, and then Peter was destined to receive yet another surprise. “Get that revolver of yours, will you, Daventry—I told you to bring one down here with you, didn’t I?” “It’s upstairs in my bedroom—I shall have to go to get it.”