the reading-lamp which stood on the desk, tilting the green shade so that the light fell full on the safe. Then, drawing a coin from his pocket, he tapped lightly on the metal door. To Hugh's surprize the sound which came forth was not the dead vibration of solid steel but the musical ring of a substance unmistakably hollow.
"Why, it's even flimsier than I thought!" he exclaimed.
Ronnie indulged in a superior smile.
"Appearances are deceptive, dear old top," he drawled. "In all probability this safe is one of the gadgets invented by the ingenious Mr. Marie for the safe-guarding of his precious secret, and the fact that no attempt has been made to open it during the time the house was empty seems to indicate that it's no common specimen of the so-called burglar-proof variety. I say 'so-called' because it’s a well-known fact that the up-to-date crook can open any safe in the world provided that he is left long enough undisturbed. But here, I repeat, we have something different. The oxy-acetylene blowpipe will cut through chilled and toughened steel as a warm knife goes through butter, but that flimsy-looking safe would beat the best outfit in the world. The doors and walls of that safe are nothing but so many shallow boxes made of ordinary iron boiler-plating. Heaven alone knows what diabolical chemical or gas is sealed up inside those hollow walls, but you may be sure that it is something quite capable of giving the coup de grâce to the enterprising cracksman who released it. The late Mr. Silas Marie had a very wide acquaintance with highly scientific methods of wafting his enemies into the inky black nowhere, and I bet he has provided something extra special for the man who tries to steal his secret by busting that safe."
Hugh could not but agree as he examined the strange contrivance, and when he discovered a small screw-valve set in one of the inner walls, and another inside the door of the safe, he felt positive that Ronnie had guessed the truth. The safe was nothing but a huge hollow tank, and the extreme care with which the outer and inner iron skins had been hermetically sealed was a silent but significant warning of the deadly possibilities which lay within. Reassured, he replaced the sealed envelope in the safe and locked the door.
There was some desultory conversation after they had returned to the library, but it was not long before Ronnie yawned and glanced at the clock.
"I think it's time that all good little boys were in bed," he declared. "I think I'll turn in now, especially as I shall have to be up pretty early in order to get to the surgery. Heigh-ho"—he yawned again—"I wish somebody would take it into his head to leave me a country house and a nice fat income. But it is always the undeserving that get all the luck. Which room do you intend to sleep in?" he asked suddenly. "Of course you'll give a wide berth to the one from which old Marie was spirited away?"
He gave a whistle of surprize as Hugh shook his head.
"Surely you're not going to sleep there—and in the same bed?"
"Why not?" There was a gleam of quiet amusement in Hugh's eyes as he asked the question. "I consider it is the most comfortable room in the house."
Ronnie shrugged and made a grimace.
"Oh, well, there's no accounting for taste. Personally, I prefer to sleep in the front, with the door locked! Bye-bye, old bean. Pleasant dreams, and all the rest of it."
