During this tirade Sturgis and Sprague had remained standing with their eyes fixed upon the gleaming carbuncles which peered at them from behind the grated peephole at the top of the stairs. The artist seemed to realize that the fight was lost. His attitude was that of a brave man accepting, with calm despair, an unpleasant but inevitable doom. The reporter had drawn his revolver at the first sound of Murdock's voice, but had immediately returned it to his pocket upon realizing that the chemist was protected by a bullet-proof grating. Now, pale and collected, he remained inscrutable. It was impossible, even for the sharp eyes of Murdock, to determine whether he was at last resigned to his fate, or whether his active mind was still on the alert for a loophole of escape. The bit of candle which he held in his hand had burned so low that at last he was unable to hold it without risk of burning his fingers. Whereupon he coolly set it down upon the stone floor, where presently the wick fell over into a pool of molten paraffine, and the flame spluttered noisily, sending fitful gleams through the darkness. "Well," continued Murdock's voice, "it is at any rate a great satisfaction to play a game with an adversary worthy of one's steel. You have played well, Mr. Sturgis. I think you would have won modestly; and you are losing as I would myself have lost, had our positions been reversed. Good-bye." The gleaming eyes disappeared from the grating, and the sliding panel closed with a metallic click. "Now then," said Sturgis to his companion, "the last chance lies in the speaking-tube. But first help me move this box." "What do you want to do with the box?" asked Sprague, who, however, did as he was bid. "It may help us to gain a little time. Put it down here." Sturgis struck a match and pointed out the spot. "On the hot-air register?" "On what looks like a hot-air register. Did you ever see a hot-air register with no apparent means of shutting off the heat?" Sprague, who stood almost over the register, suddenly threw back his head and gasped for breath. "You have discovered the secret of this death trap," said Sturgis, observing him. "Gas!" spluttered the artist. "Yes, he is going to asphyxiate us. Now, quick, to the speaking-tube! The box will somewhat retard the rush of gas; but, at the best, it is only a question of minutes before the air becomes so charged as to render respiration impossible." Sprague rushed to the speaking-tube and whistled long and loud, after which he placed his ear to the mouthpiece. "I hear some one walking," he suddenly exclaimed. The two men listened in breathless silence for an answering call. "Well, gentlemen; what can I do for you?" The words came in Murdock's voice. Sprague's eyes met those of the reporter and saw that the last faint glimmer of hope was gone. In that swift and silent interchange of thought there was resignation to the inevitable doom and the final farewell of two brave hearts.