When I had been on the trail for nearly a week, one of those gentlemen--an excellent financier, but by no means profoundly versed in the mysteries of human nature--in his imprudent zeal to find out _something_, took matters into his own hands, and came near spoiling all by alarming the robber, without detecting him. He prepared a sort of decoy letter, as he called it, well filled with pieces of tissue paper, about the size of bank-notes, and this tempting package he addressed to a cashier to whom several of the missing letters had been directed. This fell into the hands of the robber, but the experiment was rendered harmless by the fact stated by himself after his arrest, that he never stopped to read or examine any letters, except to ascertain whether they contained money. It will never be known, probably, how much good advice the criminal lost, when he committed this _tissue_ of deception to the flames, for the worthy cashier, in his well-meant zeal, supplied the place of bank-notes in the decoy package with what he doubtless considered of more value, namely, a moral lecture to the delinquent, displaying in vivid colors the folly and wickedness of his course, and closing with the warning that if he took _that_ letter, he would surely be detected! The ingenuity and shrewdness of this device cannot be too much admired. The threat contained in the letter was so well calculated to throw the culprit off his guard, that if he had read it, he would no doubt have fallen an easy prey to such cunning machinations! It was of course expected by the deviser of this scheme that the package would be preserved by the person who stole it, in order to afford the necessary evidence of crime! The pieces of tissue paper could easily have been identified, and he would naturally preserve the accompanying document with as much care as Job was ready to show to the "book" which he wished his adversary to write! Such interference as this, with an important investigation, is never warranted by any considerations whatever. The commander of an army who has laid all his plans for surprising an enemy, would feel under very slight obligations to any officious friend, who, in his impatience and ignorance of the course intended, should alarm the foe by some hasty and ill-advised attack. Thus is it in the investigations to which we refer. Secrecy is all-important to the successful issue of the plans that may be devised; and volunteer services, especially from persons destitute of experience, are quite as likely to aid the criminal as to assist those who are endeavoring to detect him. This digression has been made principally for the sake of protesting against such interference as that above mentioned, and of inducing others to abstain from similar unwarrantable experiments.