"I shall come to that presently," said Sturgis, smiling; "you must let me tell my story in my own way, if I am to tell it connectedly." "Very well," said the banker, resignedly. "Hold on, though," he exclaimed; "you speak of two sets of trails; but what is this third set of lines, marked by alternate dots and dashes?" "They represent the traces of a third individual, who will appear upon the scene later on. He has not yet received his cue. But, since you mention him, we may put him down in the cast as 'X,' the unknown quantity of the problem; for I do not yet know his name. Now, then; let me see. Where was I? Your interruption has made me lose the thread. Oh, yes; the men were in this room. Arbogast, nervous and excited, paced back and forth, like a caged animal. Chatham was more collected. It was warm in the bank, as compared with the intense cold outside; he removed his overcoat and threw it over the back of that chair in the corner. This fact is shown by the direction of the footsteps toward the chair, and by a mark directly below the arm of the chair where the garment trailed upon the wet floor. Chatham's carelessness was fraught with serious consequences; for, as luck would have it, there was, in one of the pockets of his coat, an important letter, which slipped out and fell upon the floor superscription uppermost. Here is the envelope itself, which I have pieced together. You will see that it is soiled only upon the back, and here near the chair is the faint oblong mark which it left upon the floor. Chatham went to the telephone in the cashier's office. He probably did not see the letter fall. It caught Arbogast's eye, however; and you may imagine his surprise when he saw that it was addressed to his wife. What had his accomplice to write to his wife? Arbogast evidently was not restrained by any feelings of delicacy in the matter, or else he was already suspicious of Chatham; for he picked up the envelope, tore it open, and read the letter which lies before you, as I have pieced it together. It makes interesting reading. I do not wonder that Arbogast lost his head when he saw it. Read it for yourself." "Why," exclaimed Dunlap, after reading the letter, "this announces his intention of committing suicide." "Precisely; and yet Arbogast did not commit suicide; probably never had any intention of doing so; and, at any rate, did not write that letter. You will observe that it is not signed; the name is typewritten, like the rest of the letter, which, moreover, was not written here, as the superscription would seem to indicate. I have tried your typewriter, and although it is of the same make as the one upon which this letter was written, there are several characteristic differences in the alignment and in the imperfections of the type.