After some
      business transactions, hurried through in his ordinary manner, he
      produces a letter somewhat similar to the one in question, opens
      it, pretends to read it, and then places it in close
      juxtaposition to the other. Again he converses, for some fifteen
      minutes, upon the public affairs. At length, in taking leave, he
      takes also from the table the letter to which he had no claim. Its rightful owner saw, but, of course, dared not call attention
      to the act, in the presence of the third personage who stood at
      her elbow. The minister decamped; leaving his own letter—one of
      no importance—upon the table.”

      “Here, then,” said Dupin to me, “you have precisely what you
      demand to make the ascendancy complete—the robber’s knowledge of
      the loser’s knowledge of the robber.”

      “Yes,” replied the Prefect; “and the power thus attained has, for
      some months past, been wielded, for political purposes, to a very
      dangerous extent. The personage robbed is more thoroughly
      convinced, every day, of the necessity of reclaiming her letter. But this, of course, cannot be done openly. In fine, driven to
      despair, she has committed the matter to me.”

      “Than whom,” said Dupin, amid a perfect whirlwind of smoke, “no
      more sagacious agent could, I suppose, be desired, or even
      imagined.”

      “You flatter me,” replied the Prefect; “but it is possible that
      some such opinion may have been entertained.”

      “It is clear,” said I, “as you observe, that the letter is still
      in possession of the minister; since it is this possession, and
      not any employment of the letter, which bestows the power. With
      the employment the power departs.”

      “True,” said G.; “and upon this conviction I proceeded. My first
      care was to make thorough search of the minister’s hotel; and
      here my chief embarrassment lay in the necessity of searching
      without his knowledge. Beyond all things, I have been warned of
      the danger which would result from giving him reason to suspect
      our design.”

      “But,” said I, “you are quite au fait in these investigations. The Parisian police have done this thing often before.”

      “Oh, yes; and for this reason I did not despair. The habits of
      the minister gave me, too, a great advantage. He is frequently
      absent from home all night. His servants are by no means
      numerous. They sleep at a distance from their master’s apartment,
      and, being chiefly Neapolitans, are readily made drunk. I have
      keys, as you know, with which I can open any chamber or cabinet
      in Paris. For three months a night has not passed, during the
      greater part of which I have not been engaged, personally, in
      ransacking the D—— Hotel. My honor is interested, and, to mention
      a great secret, the reward is enormous. So I did not abandon the
      search until I had become fully satisfied that the thief is a
      more astute man than myself. I fancy that I have investigated
      every nook and corner of the premises in which it is possible
      that the paper can be concealed.”

      “But is it not possible,” I suggested, “that although the letter
      may be in possession of the minister, as it unquestionably is, he
      may have concealed it elsewhere than upon his own premises?”

      “This is barely possible,” said Dupin. “The present peculiar
      condition of affairs at court, and especially of those intrigues
      in which D—— is known to be involved, would render the instant
      availability of the document—its susceptibility of being produced
      at a moment’s notice—a point of nearly equal importance with its
      possession.”

      “Its susceptibility of being produced?” said I. “That is to say, of being destroyed,” said Dupin. “True,” I observed; “the paper is clearly then upon the premises. As for its being upon the person of the minister, we may consider
      that as out of the question.”

      “Entirely,” said the Prefect. “He has been twice waylaid, as if
      by footpads, and his person rigorously searched under my own
      inspection.”

      “You might have spared yourself this trouble,” said Dupin. “D——,
      I presume, is not altogether a fool, and, if not, must have
      anticipated these waylayings, as a matter of course.”

      “Not altogether a fool,” said G., “but then he’s a poet, which I
      take to be only one remove from a fool.”

      “True,” said Dupin, after a long and thoughtful whiff from his
      meerschaum, “although I have been guilty of certain doggrel
      myself.”

      “Suppose you detail,” said I, “the particulars of your search.”

      “Why the fact is, we took our time, and we searched _everywhere_. I have had long experience in these affairs. I took the entire
      building, room by room; devoting the nights of a whole week to
      each. We examined, first, the furniture of each apartment. We
      opened every possible drawer; and I presume you know that, to a
      properly trained police agent, such a thing as a secret drawer is
      impossible. Any man is a dolt who permits a ‘secret’ drawer to
      escape him in a search of this kind. The thing is so plain. There
      is a certain amount of bulk—of space—to be accounted for in every
      cabinet. Then we have accurate rules. The fiftieth part of a line
      could not escape us. After the cabinets we took the chairs. The
      cushions we probed with the fine long needles you have seen me
      employ. From the tables we removed the tops.”

      “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.