“Why so?”

“Sometimes the top of a table, or other similarly arranged piece of furniture, is removed by the person wishing to conceal an article; then the leg is excavated, the article deposited within the cavity, and the top replaced.  The bottoms and tops of bedposts are employed in the same way.”

“But could not the cavity be detected by sounding?” I asked.

“By no means, if, when the article is deposited, a sufficient wadding of cotton be placed around it.  Besides, in our case, we were obliged to proceed without noise.”

“But you could not have removed — you could not have taken to pieces all articles of furniture in which it would have been possible to make a deposit in the manner you mention.  A letter may be compressed into a thin spiral roll, not differing much in shape or bulk from a large knitting-needle, and in this form it might be inserted into the rung of a chair, for example.  You did not take to pieces all the chairs?”

“Certainly not; but we did better — we examined the rungs of every chair in the hotel, and, indeed the jointings of every description of furniture, by the aid of a most powerful microscope.  Had there been any traces of recent disturbance we should not have failed to detect it instantly.  A single grain of gimlet-dust, for example, would have been as obvious as an apple.  Any disorder in the glueing — any unusual gaping in the joints — would have sufficed to insure detection.”

“I presume you looked to the mirrors, between the boards and the plates, and you probed the beds and the bed-clothes, as well as the curtains and carpets.”

“That of course; and when we had absolutely completed every particle of the furniture in this way, then we examined the house itself.  We divided its entire surface into compartments, which we numbered, so that none might be missed; then we scrutinized each individual square inch throughout the premises, including the two houses immediately adjoining, with the microscope, as before.”

“The two houses adjoining!” I exclaimed; “you must have had a great deal of trouble.”

“We had; but the reward offered is prodigious!”

“You include the grounds about the houses?”

“All the grounds are paved with brick.  They gave us comparatively little trouble.  We examined the moss between the bricks, and found it undisturbed.”

“You looked among D—­’s papers, of course, and into the books of the library?”

“Certainly; we opened every package and parcel; we not only opened every book, but we turned over every leaf in each volume, not contenting ourselves with a mere shake, according to the fashion of some of our police officers.  We also measured the thickness of every book-cover, with the most accurate admeasurement, and applied to each the most jealous scrutiny of the microscope.  Had any of the bindings been recently meddled with, it would have been utterly impossible that the fact should have escaped observation.  Some five or six volumes, just from the hands of the binder, we carefully probed, longitudinally, with the needles.”