The success the plan met with in India led to its trial and speedy adoption by the French and English police.  In Paris it is used as an adjunct to the measurement system of M. Bertillon, but at Scotland Yard the Bertillon system has been entirely done away with and full reliance is had on the prints.  M. Bertillon claims to have 500,000 prints in his collection, although this is said by the authorities to be an exaggeration, and Inspector McNaughton of the convict supervision office has at least 100,000 criminals’ hands catalogued in his office.

Finger marks do not change in any way through life, and any injury only temporarily affects the pattern.  The pattern becomes larger as the youth develops into a man, but the arrangement of the lines remains absolutely the same.

Thumb-marks may be generally classified as loops, arches and ovals, or whorls; the ovals irresistibly remind one of whirlpools as well as the volutions of shells, while the majority of loops or arches resemble in their convolutions the rapid movement of rushing water.

Thumb-print identifications have been extended to commercial uses by the postal savings bank on the Philippines at Manila.  This bank has recently issued a series of stamp deposit cards, on which are spaces for stamps of different values to be affixed.  When the depositor has stamps to the value of 1 peso (50 cents) on the card it is exchanged at the bank for a deposit book, showing the amount to his credit.  Opposite the lines for the owner’s signature and address is a square ruled off for the reception of his thumb-print, so that even if illiterate, depositors may readily be identified.

If any one wishes to get a thumb-print impression without the suspect’s knowledge, simply hand him a piece of paper, asking him to identify it or examine it for one reason or another, afterwards sprinkling some special black powder over it which brings out the impressions as clear as life.  Another sort of white powder is used for bringing out impressions on glassware.

Once the impression is secured, the fingers are classified according to a regular plan.  The lines on them are divided into loops, whorls, arches, and composites, the latter class made up of a collection of the first three.  Each pair of fingers as the index, little and ring fingers has a special valuation which is used to identify them and facilitate classification.  One pair will be classified according to the number of little ridges between the delta, or point where all bifurcate, and the outer ring.  If there are more than nine on one finger, it is classed as an over-nine.

It is seldom that two similar fingers are alike and the other finger usually would be an under-nine finger, say six.  So there is the first pair classified thus, 9-6.  The next two fingers may have rotary lines and are merely classified as R, the next two may not have many lines at all that will count, so are marked 0, while perhaps the last pair is unmatched, a point being allowed to one and nothing to the other.