He knew before he had finished reading that it was he who had borne the letter to the cottage in Buckeye Lane, unless there had been a series of such communications, which was unlikely on the face of it.  Mrs. Owen had herself offered confirmation by placing the delivery of the dateless letter five years earlier.  The internal evidence in the phrases prescribing the manner in which the verbal reply was to be sent, and the indorsement on the back of the sheet, were additional corroboration.  It was almost unimaginable that the letter should have come again to his hand.  He realized the importance and significance of the sheet of paper with the swiftness of a lightning flash; but beyond the intelligence conveyed by the letter itself there was still the darkness to grope in.  His wits had never worked so rapidly in his life; he felt his heart beating uncomfortably; the perspiration broke out upon his forehead, and he drew out his handkerchief and mopped his face.

“It’s certainly very curious, very curious indeed,” he said with all the calmness he could muster.  “But it doesn’t tell us much.”

“It wasn’t intended to tell anything,” said Mrs. Owen.  “Whoever wrote that letter, as I told you, was troubled about Sylvia.  I reckon it was a man; and I guess it’s fair to assume that he felt under obligations, but hadn’t the nerve to face ’em as obligations.  Is that the way it strikes you?”

[Illustration:  WHOEVER WROTE THAT LETTER WAS TROUBLED ABOUT SYLVIA]

“That seems clear enough,” he replied lamely.  He made a pretense of rereading the letter, but only detached phrases penetrated to his consciousness.  His imagination was in rebellion against the curbing to which he strove to subject it.  When he had borne his answer back to Fitch’s office and been discharged with the generous payment of one hundred dollars for his services as messenger, just what had been the further history of the transaction?  He had so far controlled his agitation that he was able to continue discussing the letter formally with the kind old woman who had placed the clue in his hands.  He was little experienced in the difficult art of conversing with half a mind, and a direct question from Mrs. Owen roused him to the necessity of heeding what she was saying.  He had resolved, however, that he would not tell her of his own connection with the message that lay on the table before them.  He needed time in which to consider; he must not add a pebble’s weight to an avalanche that might go crashing down upon the innocent.  His training had made him wary of circumstantial evidence; after all it was possible that this was not the letter he had carried to Professor Kelton.  It would be very like Mrs. Owen, if she saw that anything could be gained by such a course, to go direct to Fitch and demand to know the source of the offer that had passed through his hands so mysteriously; but Fitch had not known the contents of the letter, or he had said as