At first the bit seemed to make little impression upon the specially hardened metal, but presently a little hole appeared, and grew deeper and deeper as Gordon kept the wheel in motion. For the time being, the criminal forgot the relief fund that he hoped to appropriate, forgot even the great, unique haul he counted on obtaining from that very safe, and was lost in the joy of being at his old trade again, and handling the old, familiar tools with undiminished skill. Gh-r-rh! Gordon paused to squirt oil into the deepening hole, as the note of the revolving bit changed and grew harsher. It was working smoothly again after a moment, and the particles of metal were rapidly accumulating. Thus the work went on. One hole was sunk to the required depth, then another, and finally, after various deft operations, the inner secrets of the lock were disclosed, and the thick door swung back on noiseless hinges. A little chuckle of satisfaction sounded as the door began to move, but, by the time it was wide open, a snarl of surprise and rage burst from the criminal’s lips. CHAPTER XIX. AN UNTIMELY KNOCK. Despite the opening of the door, the interior of the safe did not meet Gordon’s eye, as he naturally had anticipated. Instead, he found himself confronted by a second door. Worse still, this second door appeared to be even more formidable than the first. Doubtless, it was not nearly so thick, of course, but the trouble was that it presented an absolutely unbroken surface. In other words, there was no knob on it, no combination, no handle, nothing to indicate how it opened, or where the lock was. It might open from left to right, or right to left—or from top to bottom, or bottom to top, for that matter. Moreover, it was only after a close and most careful scrutiny that it was possible for Green Eye to tell where the door ended, and the rest of the safe began, so tiny was the crack about it. “Of all the infernal luck!” muttered the criminal. “A trick door, evidently. Of course, I could blow it open, if I wanted to do that, but it isn’t safe to use explosives with a house full of servants. And how in thunder am I to know where the cursed lock is, if there are no outward signs of it? It may be on one side, or on the other, high or low. Have I got to keep on drilling holes at random until I stumble upon it?” It was all he could do to keep from wrecking the study in his rage. He had a temper, and he knew it was at white heat, and threatening to boil over at any moment.