Finger Prints Part 9

Hence it is evident that the second method of "_i-o_ fore-finger" is capable of dealing rapidly with 100 cases, but that the method of "no slope" will give trouble in twelve out of the hundred cases.

TABLE XII.

_Index-headings under which more than 1 per cent of the sets of Finger Prints were registered._

(500 sets observed.)

+---------------------------------------------------- _i_ and _o_ in fore-fingers. ---------------------------------------------------- No. Frequency for Index-heading. per Reference. cent. ---------- ----------------------------- --------- 1 _a l l a l l l l l l_ 12 2 _a l l i l l " " _ 16 ---------- ----------------------------- --------- 3 _i l l i l l " " _ 28 4 _o l l i l l " " _ 14 5 _o l l o l l " " _ 40 ---------- ----------------------------- --------- 6 _i l l o l l w l l l_ 12 7 _o l l o l l " " _ 14 ---------- ----------------------------- --------- 8 _o l l a l l l l l l_ 22 9 _o l w u l l " " _ 20 10 _w l l w l l " " _ 12 11 _w w w w w w w w w w_ 14 +----------------------------------------------------

--------------------------------------------------+ No slope. -------------------------------------------------- No. Frequency for Index-heading. per Reference. cent. ---------- ----------------------------- --------- I. _a l l a l l l l l l_ 12 II. _a l l l l l " " _ 22 ---------- ----------------------------- --------- III. _l l l l l l " " _ 92 ---------- ----------------------------- --------- IV. _l l l l l l w l l l_ 32 ---------- ----------------------------- --------- V. _l l l a l l l l l l_ 30 VI. _l l w l l l " " _ 30 VII. _w l l w l l " " _ 12 VIII. _w w w w w w w w w w_ 14 --------------------------------------------------+

The headings in the right half of the table include more cases than the left half, because a combination of two or more cases that severally contain less than 1 per cent of the finger prints, and are therefore ignored in the first half of the table, may exceed 1 per cent and find a place in the second half.

The entries in Table XII. are derived from a catalogue of 500 sets, and include all entries that appeared more than five times; in other words, whose frequency exceeded 1 per cent. These are the index-headings that give enough trouble to deserve notice in catalogues of, say, from 500 to 1000 sets.

In the left half of Table XII. all the index-headings are given, under each of which more than 1 per cent of the sets fell, when the method of "_i_ and _o_ in fore-fingers" was adopted; also the respective percentage of the cases that fell under them. In the right half of the table are the corresponding index-headings, together with the percentages of frequency, when the "no slope" method is employed. These are distinguished by Roman numerals. The great advantage of the "_i_ and _o_ fore-finger" method lies in its power of breaking up certain large groups which are very troublesome to deal with by the "no slope" method. According to the latter as many as 92 per cent of all the entries fall under the index-heading marked III., but according to the "_i-o_ fore-finger" method these are distributed among the headings 3, 4, and 5. The "all slopes" method has the peculiar merit of breaking up the large group Nos. 11 and VIII. of "all whorls," but its importance is not great on that account, as whorls are distinguishable by their cores, which are less troublesome to observe than their slopes.

The percentage of all the entries that fall under a single index-heading, according to the "_i-o_ fore-finger" method, diminishes with the number of entries at the following rate:--

TABLE XIII.

+----------------------------------------------------------+ Total number of entries. -------------------------- 100 300 500 ------------------------------- -------- -------- -------- Percentage of entries falling under a single head 63 490 398 +----------------------------------------------------------+

It may be that every one of the 4{2} 3{8}, or one hundred and five thousand possible varieties of index-headings, according to the "_i-o_ fore-finger" method, may occur in Nature, but there is much probability that some of them may be so rare that instances of no entry under certain heads would appear in the register, even of an enormous number of persons.

Hitherto we have supposed that prints of the ten fingers have in each case been indexed. The question now to be considered is the gain through dealing in each case with all ten digits, instead of following the easier practice of regarding only a few of them. The following table, drawn up from the hundred cases by the "all slopes" method, will show its amount.

TABLE XIV.--_From 100 Sets._

+----------------------------------------------------------------------+ No. of different index-headings. Digits. No. of ------------------------------------ digits. All _i_ and _o_ No slope. slopes. fore-finger. ----------------------- --------- --------- -------------- ----------- Fore and middle of right hand 2 11 8 7 Fore, middle and ring of right hand 3 23 16 14 Fore, middle and ring of both hands 6 65 50 45 All ten digits 10 83 76 73 +----------------------------------------------------------------------+

The trouble of printing, reading off, and indexing the ten digits, is practically twice that of dealing with the six fingers; namely, three on each of the hands; the thumb being inconvenient to print from, and having to be printed separately, even for a dabbed impression, while the fingers of either hand can be dabbed down simultaneously.

For a large collection the ten digit method is certainly the best, as it breaks up the big battalions; also in case of one or more fingers having been injured, it gives reserve material to work upon.

We now come to the great difficulty in all cla.s.sifications; that of transitional cases. What is to be done with those prints which cannot be certainly cla.s.sed as Arches, Loops, or Whorls, but which lie between some two of them? These occur about once in every forty digits, or once in every four pairs of hands. The roughest way is to put a mark by the side of the entry to indicate doubt, a better one is to make a mark that shall express the nature of the peculiarity; thus a particular eyed pattern (Plate 10, Fig. 16, _n_) may be transitional between a loop and a whorl; under whichever of the two it is entered, the mark might be an _e_ to show that anyhow it is an eye. Then, when it is required to discover whether an index contains a duplicate of a given specimen in which a transitional pattern occurs, the two headings between which the doubt lies have to be searched, and the marked entries will limit the search. Many alternative ways of marking may be successfully used, but I am not yet prepared to propose one as being distinctly the best. When there are two of these marks in the same set, it seldom happens that more than two references have to be made, as it is usual for the ambiguity to be of the same kind in both of the doubtful fingers. If the ambiguities were quite independent, then two marks would require four references, and three marks would require nine. There are a few nondescript prints that would fall under a separate heading, such as Z. Similarly, as regards lost or injured fingers.

I have tried various methods of sub-cla.s.sification, and find no difficulty in any of them, but general rules seem inadvisable; it being best to treat each large group on its own merits.

One method that I have adopted and described in the _Proc. Royal Soc._, is to sketch in a cursive and symbolic form the patterns of the several fingers in the order in which they appear in the print, confining myself to a limited number of symbols, such as might be used for printer's types.

They sufficed fairly for some thousands of the finger marks upon which they were tried, but doubtless they could be improved. A little violence has of course to be used now and then, in fitting some unusual patterns to some one or other of these few symbols. But we are familiar with such processes in ordinary spelling, making the same letter do duty for different sounds, as _a_ in the words _as_, _ale_, _ask_, and _all_. The plan of using symbols has many secondary merits. It facilitates a leisurely revision of first determinations, it affords a pictorial record of the final judgment that is directly comparable with the print itself, and it almost wholly checks blunders between inner and outer slopes. A beginner in finger reading will educate his judgment by habitually using them at first.

[Ill.u.s.tration: PLATE 2.

FIG. 3. Form of card used for impressions of the ten digits. 11-1/2 5 inches.

FIG. 4. Roller and its bearings, of a pocket printing apparatus.]

The cores give great a.s.sistance in breaking up the very large groups of all-loops (see Table XII., Nos. 11 and VIII.); so does an entry of the approximate number of ridges in some selected fingers, that lie between the core and the upper outline of the loop.

The plan I am now using for keeping finger prints in regular order, is this:--In the princ.i.p.al collection, the prints of each person's ten digits are taken on the same large card; the four fingers of either hand being _dabbed_ down simultaneously above, and all the ten digits _rolled_ separately below. (Plate 2, Fig. 3.) Each card has a hole three-eighths of an inch in diameter, punched in the middle near to the bottom edge, and the cards are kept in trays, which they loosely fit, like the card catalogues used in many libraries. Each tray holds easily 500 cards, which are secured by a long stout wire pa.s.sing like a skewer through the ends of the box and the holes in the cards. The hinder end of the box is sloped, so the cards can be tilted back and easily examined; they can be inserted or removed after withdrawing the wire.

It will be recollected that the leading and therefore the most conspicuous headings in the index refer to the fore, middle, and ring-fingers of the right hand, as entered in column A of the Specimen Register (Table IX.) The variety of these in the "_i_ and _o_ fore-finger" method, of which we are now speaking, cannot exceed thirty-six, there being only four varieties (_a_, _i_, _o_, _w_) in the fore-finger, and three varieties (_a_, _l_, _w_) in each of the other two; so their maximum number is 4 3 3 = 36. The actual number of such index-headings in 500 cases, and the number of entries that fell under each, was found to be as follows:--

TABLE XV.

_No. of entries in 500 cases, under each of the thirty-six possible index-letters for the fore, middle, and ring-fingers of the right hand by the "i-o fore-finger" method._

+--------------------------------------------------------------+ _a a a_ 4 _i a a_ 1 _o a a_ 1 _w a a_ -- _l_ 17 _l_ 3 _l_ 2 _l_ -- _w_ 5 _w_ -- _w_ 1 _w_ 1 _a l a_ 3 _i l a_ -- _o l a_ 2 _w l a_ 1 _l_ 45 _l_ 54 _l_ 88 _l_ 40 _w_ 11 _w_ 33 _w_ 59 _w_ 52 _a w a_ -- _i w a_ -- _o w a_ -- _w w a_ -- _l_ -- _l_ 3 _l_ -- _l_ 10 _w_ -- _w_ 11 _w_ 6 _w_ 47 +--------------------------------------------------------------+

_a_ = Arch.

_i_ = Inward-sloped Loop on the fore-finger.

_o_ = Outward-sloped Loop on the fore-finger.

_l_ = Loop of either kind on the middle or ring finger.

_w_ = Whorl.

These 500 cases supply no entries at all to eleven of the thirty-six index-headings, less than five entries (or under 1 per cent) to ten others, and the supply is distributed very unevenly among the remaining fifteen. This table makes it easy to calculate beforehand the s.p.a.ces required for an index of any specified number of prints, whether they be on the pages of a Register, or in compartments, or in drawers of movable cards.

CHAPTER X

PERSONAL IDENTIFICATION

We shall speak in this chapter of the aid that finger prints can give to personal identification, supposing throughout that facilities exist for taking them well and cheaply, and that more or less practice in reading them has been acquired by many persons. A few introductory words will show this supposition to be reasonable. At the present moment any printer, and there are many printers in every town, would, at a small charge, blacken a slab and take the prints effectively, after being warned to use very little ink, as described in Chapter III. The occupation of finger printing would, however, fall more naturally into the hands of photographers, who, in addition to being found everywhere, are peculiarly well suited to it, for, taken as a cla.s.s, they are naturally gifted with manual dexterity and mechanical ingenuity. Having secured good impressions, they could multiply them when necessary, and enlarge when desired, while the ticketing and preservation of the negatives would fall into their usual business routine. As they already occupy themselves with one means of identification, a second means of obtaining the same result is allied to their present work.

Were it the custom for persons about to travel to ask for prints of their fingers when they were photographed, a familiarity with the peculiarities of finger prints, and the methods of describing and cla.s.sifying them, would become common. Wherever finger prints may be wanted for purposes of attestation and the like, the fact mentioned by Sir W. Herschel (p. 45) as to the readiness with which his native orderlies learnt to take them with the ink of his office stamp, must not be forgotten.

The remarks about to be made refer to identification generally, and are not affected by the fact that the complete process may or may not include the preliminary search of a catalogue; the two stages of search and of comparison will be treated separately towards the close of the chapter.

In civilised lands, honest citizens rarely need additional means of identification to their signatures, their photographs, and to personal introductions. The cases in which other evidence is wanted are chiefly connected with violent death through accident, murder, or suicide, which yield the constant and gruesome supply to the Morgue of Paris, and to corresponding inst.i.tutions in other large towns, where the bodies of unknown persons are exposed for identification, often in vain. But when honest persons travel to distant countries where they have few or no friends, the need for a means of recognition is more frequently felt. The risk of death through accident or crime is increased, and the probability of subsequent identification diminished. There is a possibility not too remote to be disregarded, especially in times of war, of a harmless person being arrested by mistake for another man, and being in sore straits to give satisfactory proof of the error. A signature may be distrusted as a forgery. There is also some small chance, when he returns to his own country after a long absence, of finding difficulty in proving who he is.

But in civilised lands and in peaceable times, the chief use of a sure means of identification is to benefit society by detecting rogues, rather than to establish the ident.i.ty of men who are honest. Is this criminal an old offender? Is this new recruit a deserter? Is this professed pensioner personating a man who is dead? Is this upstart claimant to property the true heir, who was believed to have died in foreign lands?

In India and in many of our Colonies the absence of satisfactory means for identifying persons of other races is seriously felt. The natives are mostly unable to sign; their features are not readily distinguished by Europeans; and in too many cases they are characterised by a strange amount of litigiousness, wiliness, and unveracity. The experience of Sir W. Herschel, and the way in which he met these unfavourable conditions by the method of finger prints, has been briefly described in p. 27. Lately Major Ferris, of the Indian Staff Corps, happening to visit my laboratory during my absence, and knowing but little of what Sir W. Herschel had done, was greatly impressed by the possibilities of finger prints. After acquainting himself with the process, we discussed the subject together, and he very kindly gave me his views for insertion here. They are as follow, with a few trifling changes of words:--