The reader can easily see that in all cases where a crime, such as forgery, is concerned, once the identity of the criminal is ascertained, half the work (or more than half) is done.  The agencies know the face and record of practically every man who ever flew a bit of bad paper in the United States, in England, or on the Continent.  If an old hand gets out of prison his movements are watched until it is obvious that he does not intend to resort to his old tricks.  After the criminal is known or “located,” the “trailing” begins and his “connections” are carefully studied.  This may or may not require what might be called real detective work; that is to say, work requiring superior power of deducing conclusions from first-hand information, coupled with unusual skill in acting upon them.  Mere trailing is often simple, yet sometimes very difficult.  A great deal depends on the operator’s own peculiar information as to his man’s habits, haunts, and associates.  It is very hard to say in most cases just where mere knowledge ends and detective work proper begins.  As for disguises, they are almost unknown, except such as are necessary to enable an operator to join a gang where his quarry may be working and “rope” him into a confession.

Detective agencies of the first-class are engaged principally in clean-cut criminal work, such as guarding banks from forgers and “yeggmen”—­an original and dangerous variety of burglar peculiar to the United States and Canada.  In other words, they have large associations of clients who need more protection than the regular police can give them, and whose interest it is that the criminal shall not only be driven out of town, but run down (wherever he may be), captured, and put out of the way for as long a time as possible.

The work done for private individuals is no less important and effective, but it is secondary to the other.  The great value of the “agency” to the victim of a theft is the speed with which it can disseminate its information—­something quite impossible so far as the individual citizen is concerned.  Let me give an illustration or two.

Between 10.30 P.M.  Saturday, February 25, 1911, and 9.30 A.M.  Sunday, February 26, 1911, one hundred and thirty thousand dollars worth of pearls belonging to Mrs. Maldwin Drummond were stolen from a stateroom on the steamship ‘Amerika’ of the Hamburg-American line.  The London underwriters cabled five thousand dollars reward and retained to investigate the case a well-known American agency, which before the ‘Amerika’ had reached Plymouth on her return trip had their notifications in the hands of all the jewelers and police officials of Europe and the United States, and had covered every avenue of disposal in North and South America.  In addition, this agency investigated every human being on the Amerika from first cabin to forecastle.

Within a year or so an aged stock-broker, named Bancroft, was robbed on the street of one hundred thousand dollars in securities.  Inside of fifty-five minutes after he had reported his loss a detective agency had notified all banks, brokers, and the police in fifty-six cities of the United States and Canada.