"I guess I'd better stop thinking of her and attend strictly to this disappearance business," he murmured as he went up the steps of the Potter mansion. "She's too rich for one thing, and another is I'm too poor, though I'm earning good wages, and we have some money in the bank," for the sale of the Bronx land, as related in "Larry Dexter, Reporter," had netted Mrs. Dexter and her children about ten thousand dollars. Larry's ring at the bell was answered by Grace, who, it would seem, had been on the watch for him. "I thought you would never come," she said. "I telephoned ever so long ago." "I came as fast as I could," Larry responded. "Where is the letter?" Grace held out to him a small piece of paper. On it was but a single line of writing. It read: "Am well. Have to stay away for a time. Don't worry. Will write again." It was signed with Mr. Potter's name. "Are you sure it's from your father?" asked Larry, thinking some cruel person might be trying to play a joke, or that some enterprising reporter had sent the message for the sake of making news. Such things are sometimes done by New York newspaper men, though their city editors may know nothing about it. "I couldn't mistake father's writing," replied Grace. "Mamma knows it is from him, and she is much happier. But we can't imagine why he has to stay away." "When did you get this, and how did it come?" asked the reporter. "The postman brought it a little while ago." "Where is the envelope?" Grace handed it to Larry. An inspection of the post-mark showed that it had been mailed in New York in the vicinity of sub-station Y, which was on the East Side. It might have been dropped in one of the many street boxes from which collections were made for that particular office, or it might have been mailed in the station itself. "Not much to trace him by," said Larry. He looked at the envelope again and saw that there was a small ink blot on the lower left-hand corner, and that the corner where the stamp was affixed was smeared as if with some sticky substance. "Any one would think you were a detective," said Grace, as she watched Larry examining the envelope. "What does it matter now? We are sure father is alive, for that note was posted yesterday. That has made mother and me happy. Of course we want to find him, but I don't see how you can by that letter. I thought you'd like to know about it to make a little item for the paper, and I wanted to repay you for your kindness to mother and me." "I haven't done anything," Larry replied. "I am only too glad to be of service to you. But I may be able to find out something by this envelope." "I don't see how." "Will you let me take it to the sub-station?" "Of course. But what good will that do?" "I want to ask the sorters and clerks in charge if they remember having handled it. I may find the carrier who brought it in from the box, and he can tell in what locality it was."