Wells, Fargo & Co. had given him every assistance in their power to discover who had sold that bill to the California branch of their house; but an answer had been returned from there that the person who disposed of it was a stranger, on his way to the mining regions, whom they had never seen before or since, and whose name they had not taken. The clerk who transacted the brief business with him, had no distinct recollection of him, except that he was rather a thick-set man, with an unpleasant expression--doubtless one of the "hard cases" so frequent in the precincts of San Francisco. Of course, it was clear to us two, who sat in company with the dead-letter, that the five-hundred-dollar bill was a part of the sum referred to by the writer; that it had come out of Mr. Argyll's desk, and that it was blood-money paid for a murder; and the receiver was this person who, in the letter, so explicitly declared his intention of fleeing to California. We were much excited in the presence of these bold facts. In our enthusiasm, then, it seemed easy to stretch a hand across the continent and lay it upon the guilty. We scarcely realized the long and wearisome pursuit to which we were doomed--the slight clue which we had to the individual whose deeds were yet so patent to us. At this revelation of conspiracy, my mind eagerly searched about for the accessory, and again settled itself upon Miss Sullivan. It did seem to me that she had thrown a glamour over the usually clear sight of Mr. Burton; so that I resolved to keep a separate watch which should not be influenced by his decisions. While I was thinking of this, Mr. Burton was walking about the floor. Suddenly he stopped before me and looked into mine with those vivid eyes, so full of power, and said, as confidently as if a vision had revealed it to him, "I have now made out all the meaning of the letter. In the first place, it is written '_by contraries_'--that is, it means just the contrary of what it says. The contract _was_ fulfilled. The price was expected, the emigration decided upon. The bright day was a rainy night; the picture taken was a human life. And, don't you see it, Richard?--the old friend was the hiding-place of the instrument of death, after which the accomplice is directed to look. That instrument is the broken tooth-pick. It was secreted in the pocket of the old friend. Now, who or what is this old friend? Richard, didn't Leesy affirm she saw a man descending from the old oak tree at the right of the Argyll mansion, on the evening of the murder?" "She did." "Then _that_ is it. I want to know no more. The arms are the arms of that old oak. Unless it has been removed, which is not probable, since this letter was never received, the broken knife or dagger (of which I have the point which was taken from the wound), will be found in some hollow on the left side of that oak."