The distance from this place to the town where the academy was situated, was about twenty miles, and the next thing to be done was to ascertain whether F. had been there within a week or two. A little reflection suggested a tolerably safe and direct mode of ascertaining this fact, which was, to see the merchant before referred to, as being cognisant of the passing of the twenty dollar notes, who had already been partially informed of the object of my former inquiries concerning them; and to request him to address a line to Mr. F., inquiring whether he recollected seeing a person, apparently insane, in the stage-coach, while on his way home after the Exhibition. This certainly could do no harm in case he was not present on that occasion, while if he had been, he would very naturally confirm the fact in answering the question proposed. The next mail brought a reply to the effect that he did not return home by the stage, but in his own private conveyance, and therefore saw no such person as the one inquired about. I had thus made a beginning in laying a foundation for the superstructure of evidence which I was endeavoring to raise; a foundation, of which a tight coat was the corner-stone. If Mr. F.'s outer garment had not required alteration, I should, up to this time, have failed in establishing a most important fact, viz., his probable identity with the individual who passed the bank notes; and as long as this point was involved in much uncertainty, I should hardly have felt prepared to push my researches with much energy or hope. The following facts were now in my possession: Mr. F. was in the same town where the Exhibition was held, and upon that occasion; his general appearance corresponded to that of the person who had then and there exchanged the notes; and his position as post master gave him sufficient opportunities to have committed the robberies. All this seemed to authorize and require more definite and concentrated measures on my part. In the mail from Boston, which was to pass on that route on the following day, sundry tempting-looking packages might have been found, which were not altogether valueless in a pecuniary point of view, and would assuredly have been missed had they been stopped anywhere short of their place of destination. In other words, these packages were what are called _decoy letters_,--a species of device for entrapping the dishonest, which will always be effectual, and whose detective power the shrewdest rogue is unable to withstand. The utmost sagacity will never enable one to distinguish between a decoy-letter and a genuine one, so that the only way of securing safety from these missives is to let all letters alone. The coat of arms of Scotland--a thistle, with the motto "_Noli me tangere_,"--would be an appropriate device for these paper bomb-shells.