“I don’t understand,” said he.  “What do you expect to find?”

“Some spring or button by which this floor is made to serve the purpose of a trap.  I’m sure that there is an opening underneath—­a large opening.  Won’t you help me—­”

I forgot to finish.  In my eagerness to impress him I had turned in his direction, and was staring straight at his easy figure and faintly smiling features, when the molding against which he leaned caught my eye.  With a total absence of every other thought than the idea which had suddenly come to me, I sprang forward and pressed with my whole weight against one of the edges of the molding which had a darker hue about it than the rest.  I felt it give, felt the floor start from under me at the same moment, and in another heard the clatter and felt the force of the toppling cabinet on my shoulder as it and I went shooting down into the hole I had been so anxious to penetrate, though not in just this startling fashion.

The cry, uttered by Mr. Steele as I disappeared from before his eyes, was my first conscious realization of what had happened after I had struck the ground below.

“Are you hurt?” he cried, with real commiseration, as he leaned over to look for me in the hollow at his feet.  “Wait and I will drop down to you,” he went on, swinging himself into a position to leap.

I was trembling with the shock and probably somewhat bruised, but not hurt enough to prevent myself from scrambling to my feet, as he slid down to my side and offered me his arm for support.

“What did you do?” he asked.  “Was it you who made this trap give way?  I see that it is a trap now,”—­and he pointed to the square boarding hampered by its carpet which hung at one side.

“I pressed one of those round knobs in the molding,” I explained, laughing to hide the tears of excitement in my eyes.  “It had a loose look.  I did it without thinking,—­that is, without thinking enough of what I was doing to be sure that I was in a safe enough position for such an experiment.  But I’m all right, and so is the cabinet.  See!” I pointed to where it stood, still upright, its contents well shaken up but itself in tolerably good condition.

“You are fortunate,” said he.  “Shall I help you up out of this?  Your curiosity must be amply satisfied.”

“Not yet, not yet,” I cried.  “Oh! it is as I thought,” I now exclaimed, peering around the corner of the cabinet into a place of total darkness.  “The passage is here, running directly under the alley-way.  Help me, help me, I must follow it to the end.  I’m sure it communicates with the house next door.”

He had to humor me.  I already had one hand on the cabinet’s edge, and should have pushed it aside by my own strength if he had not interfered.  The space we were in was so small, some four feet square, I should judge, that the utmost we could do was to shove one corner of it slightly aside, so as to make a narrow passage into the space beyond.  Through this I slipped and should have stepped recklessly on if he had not caught me back and suggested that he go first into what might have its own pitfalls and dangers.