Or, perhaps, you have the best accredited fiction idea of the unraveler of mysteries. This creation is a tall, cadaverous individual, who sits on the small of his back in a morris-chair and smokes a pipe. From a leaf torn from last year's almanac, in an East Side garret, he draws the conclusion that the perpetrator of a Black Hand outrage in Xenia, Ohio, is a pock-marked Hungarian now floating down the Mississippi on a scow; he radiographs with the aid of a weird instrument at his elbow and apprehends the fugitive. Of these two conceptions of detectives it may be said that the first is quite correct: that the graduate policeman is abroad in the land, lumbering along on the trail of its criminals and occasionally catching one of them. His assignment to this task is, obviously, a bit like thrusting the work of a fox upon a ponderous elephant. The police departments, however, are practically the only training schools for detectives and it is but natural that they should be drawn upon. Of the second conception of the detective--the man of science and deductions--it may be said merely that he does not exist in all the world, nor could exist. There is one case in a hundred which would require the man of science in its solution and upon which he might work much as he does in fiction. In the ninety-nine there would be no place for such talents as his. For each criminal case is a problem separate unto itself, and there may not be brought to it more than a trained, logical, imaginative mind, which may unfold it and see all the possibilities. There is but the occasional call upon science, and the good detective knows when to consult the specialist. It was little more than half a dozen years ago that the Federal Department of Justice set about the upbuilding of the greatest detective bureau that the Government, or America for that matter, has ever known. As the Bureau of Investigation it was to have charge of all the secret work of the Government for which provision was not made elsewhere. It was to wrestle with violations of neutrality, with those of the national banking laws, with anti-trust cases, bucket shop cases, white slave cases; it was to prosecute those who impersonate an officer of the Government, to pursue those who flee the country and seek to evade the long arm of the Federal law. Its duties were vastly wider than those of any other of the Government detective agencies. Department of Justice cases are stupendously big in many instances. They may affect the relations that exist between nations, they may mean the wrecking of hundred-million-dollar corporations, the stopping of practises that are blights upon the morality and good name of the nation. They are endless in variety and stupendous in their results.