of the
work for which detectives are employed is not in the detection of
crime and criminals, but in simply watching people, following them, and
reporting as accurately as possible their movements. These functions are
known in the vernacular as spotting, locating, and trailing. It
requires patience, some powers of observation, and occasionally a little
ingenuity. The real detective under such circumstances is the man to
whom they hand in their reports. Yet much of the most dramatic and
valuable work that is done involves no acuteness at all, but simply a
willingness to act as a spy and to brave the dangers of being found out.

There is nothing more thrilling in the pages of modern history than the
story of the man (James McPartland) who uncovered the conspiracies of
the Molly McGuires. But the work of this man was that of a spy pure and
simple.

Another highly specialized class of detectives is that engaged in police
and banking work, who by experience (or even origin) have a wide and
intimate acquaintance with criminals of various sorts, and by their
familiarity with the latters' whereabouts, associates, work, and methods
are able to recognize and run down the perpetrators of particular
crimes.

Thus, for example, there are men in the detective bureau of New York
City who know by name, and perhaps have a speaking acquaintance with,
a large number of the pick-pockets and burglars of the East Side. They
know their haunts and their ties of friendship or marriage. When any
particular job is pulled off they have a pretty shrewd idea of who is
responsible for it and lay their plans accordingly. If necessary,
they run in the whole gang and put each of them through a course of
interrogation, accusation, and browbeating until some one breaks down
or makes a slip that involves him in a tangle. These men are special
policemen whose knowledge makes them detectives by courtesy. But
their work does not involve any particular superiority or quickness of
intellect--the quality which we are wont to associate with the detection
of crime.

Now, if the ordinary householder finds that his wife's necklace has
mysteriously disappeared, his first impulse is to send for a detective
of some sort or other. In general, he might just as well send for his
mother-in-law. Of course, the police can and will watch the pawnshops
for the missing baubles, but no crook who is not a fool is going to
pawn a whole necklace on the Bowery the very next da