He oiled the apple, heaped a little plaster in a newspaper, took my water-jug, and rapidly pulled off a hard mold.  The parts corresponding to the merely broken places in the apple were, of course, dissimilar; but as to the teeth-marks, the impressions were identical.

“That will do, I think,” Hewitt said.  “Tomorrow morning, Brett, I shall put up these things in a small parcel, and take them round to Bow Street.”

“But are they sufficient evidence?”

“Quite sufficient for the police purpose.  There is the man, and all the rest—­his movements on the day and so forth—­are simple matters of inquiry; at any rate, that is police business.”

* * * * *

I had scarcely sat down to my breakfast on the following morning when Hewitt came into the room and put a long letter before me.

“From our friend of last night,” he said; “read it.”

This letter began abruptly, and undated, and was as follows: 

“TO MARTIN HEWITT, ESQ.

“SIR:  I must compliment you on the adroitness you exhibited this evening in extracting from me my name.  The address I was able to balk you of for the time being, although by the time you read this you will probably have found it through the Law List, as I am an admitted solicitor.  That, however, will be of little use to you, for I am removing myself, I think, beyond the reach even of your abilities of search.  I knew you well by sight, and was, perhaps, foolish to allow myself to be drawn as I did.  Still, I had no idea that it would be dangerous, especially after seeing you, as a witness with very little to say, at the inquest upon the scoundrel I shot.  Your somewhat discourteous seizure of my apple at first amazed me—­indeed, I was a little doubtful as to whether you had really taken it—­but it was my first warning that you might be playing a deep game against me, incomprehensible as the action was to my mind.  I subsequently reflected that I had been eating an apple, instead of taking the drink he first offered me, in the dead wretch’s rooms on the night he came to his merited end.  From this I assume that your design was in some way to compare what remained of the two apples—­although I do not presume to fathom the depths of your detective system.  Still, I have heard of many of your cases, and profoundly admire the keenness you exhibit.  I am thought to be a keen man myself, but, although I was able, to some extent, to hold my own to-night, I admit that your acumen in this case alone is something beyond me.

“I do not know by whom you are commissioned to hunt me, nor to what extent you may be acquainted with my connection with the creature I killed.  I have sufficient respect for you, however, to wish that you should not regard me as a vicious criminal, and a couple of hours to spare in which to offer you an explanation that will convince you that such is not altogether the case.  A hasty and violent