Without information, the hands of the executive are tied; without informers, they would be wholly ineffective; and except for a chance seizure now and then, there would be little for them to do. As things are, the organization of a detective department is so linked up with informers and information that one finds it difficult to conceive of its existing with these eliminated. Detectives of the Sherlock Holmes type exist only in fiction, and although it goes without saying that powers of observation above the ordinary, and an intimate knowledge of men are indispensable in a detective, it is equally indispensable that a detective, as things are, must rely upon information if he wishes successfully to solve any problem of crime. In writing about informers, I deal mainly with the professional blackguards who make a regular living out of giving information. I do not include those who, to work off a grudge, or who, having seen a crime committed, lodge information in the proper quarter.—I do not look upon these as _informers_. The first is a mean-minded person; the second, one who has a very proper conception of his duty towards society. But the man I deal with is essentially a blackguard, and a very despicable blackguard at that. He has only one object in view when he gives information, and that object is money. He is not burdened with notions of his duty as a citizen. If there was no money to be made out of giving information, he would be the last to go a step out of his way to give any; but he recognizes his value as an important factor in detection, places a price on it, and is paid generously. I have often been asked by magistrates whether my informers were respectable men. I have felt no hesitation in answering the question emphatically in the negative, and I have no doubt I often set them wondering. But one has only to give the matter a moment’s consideration to see how diametrically opposed to all one’s notions of fair-play and honour must be the nature and calling of an informer. He must for a time pose as the friend and confidant of his victim, and then turn traitor; and he must bribe, coerce, and wheedle from their allegiance scores of subordinates who would otherwise serve their masters with unswerving loyalty. He is the tempter _in excelsis_; he is unscrupulous in the extreme; he is utterly bad. But for all this, he is, as I have already said, a very necessary link in the chain of detection, and we may, like the pharisee, take comfort in the thought that we are not as other men are—even as these informers! The “_unco gude_” would find a monotonous sameness in their existence if there were none to set-off their unco gudeness!