Time passed so rapidly and so pleasantly in the company of Mary Black that Herbert was loath to leave. A look at his watch, however, showed that he had less than an hour before the time would arrive for keeping his appointment, so he bade good-by to Mr. and Mrs. Black and hurried towards the door. Mary accompanied him there, and he noticed from her constrained manner that she had something on her mind and was anxious to speak to him privately. Being a man, he felt that it was incumbent upon him to break the ice, so he said gently:
“Mary, is there anything I can do for you or your father or mother? If so, don’t hesitate to speak to me frankly.”
“There is something, Herbert,” she said, “and it has been weighing upon my mind for a long while. It is about Arthur. I want you to promise me that you will be a friend to my brother. I do not believe that he is a bad boy at heart; but unfortunately, he has fallen into bad company and has been led astray. Promise me that if the opportunity ever presents itself, you will give him a helping hand. This chance may come, or it may never come; but tell me that you will not forget what I have said to you.”
Herbert took her by the hand, and said with much solemnity:
“Mary, if I ever meet Arthur and have the opportunity of befriending him, I promise you that I shall do so.”
Her eyelashes were wet with tears; but at his words, her eyes sparkled with satisfaction, and she exclaimed eagerly:
“Oh, I thank you so much for saying that, because I know that I can trust you, and I know that you mean what you say.”
A few minutes later Herbert was once more in the sub-way, speeding towards the Park Row station, which was within a short distance of the main post office building. He reached that busy spot at ten minutes of twelve o’clock and found the detective awaiting him. The two men held a hurried interview with the clerk of the box department, who informed them that he knew the young man who was in the habit of calling for the letters for the swindling concern which they now had under suspicion. He said that he would remain at his post for the next fifteen or twenty minutes and as soon as he identified the fellow he would give the two men a signal by holding up his right hand. The details of the plan having been arranged, the reporter and the detective set themselves to wait for the critical moment. It proved to be a great strain on all concerned. The hands of the big clock moved around so slowly that they could almost have shrieked out with impatience and anxiety. A great crowd was hurrying to and fro and opening and closing the letter boxes, which reached almost from the pavement to the ceiling all along the great corridor, but the moments dragged by and the clerk had made no signal.