The first thing is to locate the assassin.  An Italian detective is sent into the mine as a laborer.  Months may elapse before he gets on familiar or intimate terms with his fellows.  All the time he is listening and watching.  Presently he hears something that indicates that the murderer is communicating with one of his old friends either directly or through third parties.  It is then generally only a question of time before his whereabouts are ascertained.  Once he is “located” the same method is followed in securing additional evidence or material in the nature of a confession or admission tending to establish guilt.  Having previously “roped” the murderer’s friends, the detective now proceeds to the more difficult task of “roping” the murderer himself.  Of course, the life of a detective in a Pennsylvania coal mine would be valueless if his identity were discovered, and yet the most daring pieces of detective work are constantly being performed under these and similar conditions.  Where the criminal is not known, the task becomes far more difficult and at times exceedingly dangerous.

One of my own friends, an Italian gentleman, spent several months in the different mines of this country, where Italians are largely employed, investigating conditions and ascertaining for the benefit of his government the extent to which anarchy was prevalent.  It was necessary for him to secure work as a miner at the lowest wages and to disguise himself in such a way that it would be impossible for anybody to detect his true character.  Fortunately, the great diversity of Italian dialects facilitated his efforts and enabled him to pass himself off as from another part of the country than his comrades.  Having made his preparations he came to New York as an immigrant and joined a party of newly arrived Italians on their way to the coal mines of West Virginia.  Without following him further, it is enough to say that during his service in the mines he overheard much that was calculated to interest exceedingly the authorities at Rome.  Had his disguise been penetrated the quick thrust of a five-inch blade would have ended his career.  He would never have returned to New York.  There would only have been another dead “Dago” miner.  The local coroner would have driven up in his buggy, looked at the body, examined the clean, deep wound in the abdomen, shrugged his shoulders, and empanelled a hetrogeneous jury who would have returned a verdict to the effect that “deceased came to his death through a stab wound inflicted by some person to the jury unknown.”  My friend was not a professional detective, but the recital of his experiences was enough to fill me with new respect for those engaged in the “man hunt” business among the half civilized miners of the coal regions.

But the work of even the “national” agencies is not of the kind which the novel-reading public generally associates with detectives—­that is to say, it rarely deals with the unravelling of “mysteries,” except the identity of passers of fraudulent paper and occasional murderers.  The protection of the banks is naturally the most important work that such an agency can perform.