Before they could answer, Miss Verinder called to me softly.  She met me at the door of her room, with a light shawl, and with the counterpane from her own bed.

“Do you mean to watch him while he sleeps?” she asked.

“Yes, I am not sure enough of the action of the opium in his case to be willing to leave him alone.”

She handed me the shawl and the counterpane.

“Why should you disturb him?” she whispered.  “Make his bed on the sofa.  I can shut my door, and keep in my room.”

It was infinitely the simplest and the safest way of disposing of him for the night.  I mentioned the suggestion to Mr. Bruff and Betteredge—­who both approved of my adopting it.  In five minutes I had laid him comfortably on the sofa, and had covered him lightly with the counterpane and the shawl.  Miss Verinder wished us good night, and closed the door.  At my request, we three then drew round the table in the middle of the room, on which the candle was still burning, and on which writing materials were placed.

“Before we separate,” I began, “I have a word to say about the experiment which has been tried to-night.  Two distinct objects were to be gained by it.  The first of these objects was to prove, that Mr. Blake entered this room, and took the Diamond, last year, acting unconsciously and irresponsibly, under the influence of opium.  After what you have both seen, are you both satisfied, so far?”

They answered me in the affirmative, without a moment’s hesitation.

“The second object,” I went on, “was to discover what he did with the Diamond, after he was seen by Miss Verinder to leave her sitting-room with the jewel in his hand, on the birthday night.  The gaining of this object depended, of course, on his still continuing exactly to repeat his proceedings of last year.  He has failed to do that; and the purpose of the experiment is defeated accordingly.  I can’t assert that I am not disappointed at the result—­but I can honestly say that I am not surprised by it.  I told Mr. Blake from the first, that our complete success in this matter depended on our completely reproducing in him the physical and moral conditions of last year—­and I warned him that this was the next thing to a downright impossibility.  We have only partially reproduced the conditions, and the experiment has been only partially successful in consequence.  It is also possible that I may have administered too large a dose of laudanum.  But I myself look upon the first reason that I have given, as the true reason why we have to lament a failure, as well as to rejoice over a success.”

After saying those words, I put the writing materials before Mr. Bruff, and asked him if he had any objection—­before we separated for the night—­to draw out, and sign, a plain statement of what he had seen.  He at once took the pen, and produced the statement with the fluent readiness of a practised hand.

“I owe you this,” he said, signing the paper, “as some atonement for what passed between us earlier in the evening.  I beg your pardon, Mr. Jennings, for having doubted you.  You have done Franklin Blake an inestimable service.  In our legal phrase, you have proved your case.”