and the interior of an ordinary
City office. Men pore over foolscap sheets of paper with magnifying
glasses, comparing, classifying, and checking, day in, day out.

They are all detectives, but their work is specialist work, totally
different to that of the bulk of the men of the C.I.D. It may be that
sometimes they realise that a man's life or liberty depends on their
scrutiny, but for the most part they do their work with cold
deliberation and machine-like precision. Is one set of finger-marks
identical with another? That is all they have to answer. It is the pride
of the department that since it has been established it has never made a
mistake.

At its head is Chief Detective Inspector Charles Collins, an enthusiast
in identification work, who has seen the system change from the old days
when detectives paid periodical visits to Holloway Prison to see if they
could recognise prisoners on remand, and when profile and full-face
photographs were used for the records, to that now in use which he has
had no small share in bringing to its high state of efficiency.

He can read a finger-print as other men can read a letter, and has even,
for the purposes of study, taken prints of the fingers of monkeys at the
Zoo. Many times has he given evidence as an expert in cases where
finger-prints have formed part of the evidence. His cold, scientific
analysis has always convinced the most sceptical, and always a
conviction has followed.

He wrote the chapter dealing with the photographing and enlarging of
finger-prints in Sir Edward Henry's standard work on the subject, and is
something of a magician in the way he can detect a mark when none is
obvious to the naked eye.

I have seen a man press his fingers on a clean sheet of paper,
apparently without leaving the faintest trace. But Mr. Collins is not
baffled so. A pinch of black powder--graphite is commonly
used--scattered over the paper, and behold the prints standing out in
high relief. A grey powder will act in the same way on a dark surface,
and a candle which has been pressed by the fingers may have the print
rendered clear by a judicious use of ordinary printer's ink.

A corps of expert photographers, equipped with the latest appliances, is
attached to the department, and their services are in constant
requisition by the C.I.D. for many purposes other than those of
finger-prints. One room is entirely devoted to a powerful lantern
apparatus by which every photograph may