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ridge may have an oval eye-like end to it, the long axis of the oval being in line with the ridge. A loop is distinguished
side, so that any new systems of ridges entering into it must do so from above or below the deltas. Three arrangements are found to obtain as regards the relative positions of the ridges forming the lower prong or base of each delta. If the two prongs A C, D F pass in opposite directions across the phalanx without any other ridge intervening or are separated by not more than two ridges, they are regarded as meeting. The lower prong or ridge A, of the left delta (that is following the ridge impression from the observers left to his right, as in reading a line of print, irrespective of the hand from which the impression is taken) may pass along with three or more proximally situated ridges into the interspace inside the right delta, or the left prong or ridge may pass across the phalanx proximally to,
from an arch of the tented variety, which most nearly resembles it, by the presence of at least one ridge between the outer and inner terminuses of the loop.
The Whorl, Fig. 5 (diagramatic), is so named from the peculiar manner in which the ridges are coiled on the central part of the phalanx. The arrangement of the ridges forming the boundaries of the interspace between the almost horizontal ridges immediately beyond the creaselines of last joint and the more distal arched ridges on the point of the digit, is also characteristic and will be considered first. It is a repetition on each side of the terminal phalanx of that which obtains on one side only in the formation of the delta in the loop pattern previously
that is to say, outside, the right delta, while the three or more ridges interven-, ing between the fork ridges will pass from right to left into the interspace and assist in filling it up. A corresponding arrangement may occur in respect of the upper prongs B E as they cross each other at the top of the interspace. The core of the whorl may therefore be fed from below and above only-or from above only, but sometimes it is not supplied with ridges from either of these sources to any extent, and is mainly dependent upon a series of its own arising within the interspace. From what has been stated it will be perceived that considerable variation exists in the appearance presented by the core of a whorl. It may consist of a series of concentric ridges arranged in circular
described. In other words, in the whorl there are two deltas present 2 and Y, and the interspace is therefore closed on either
which the points of the core are situated, passing outwards on the same side of the right delta.
The central pocket loops, Fig. 11, conforms to the loop type as regards the outer ridges filling the interspace, but a few ridges immediately round the core present the appearance of a whorl. Close to the latter the second delta is situated, though
sufficiently conform to the definitions of any of the other groups to be regarded as one or other of them.
The relative frequency of these various patterns is in round numbers: Arches, five per cent; loops, sixty per cent; whorls and composites, thirty-five per cent. The greatest variety of patterns is found on the forefinger and the least vari. ation occurs on the little finger; whorls are most frequently met with on the thumb and ring finger; loops on the little and middle finger, and arches on the forefinger. The fore-finger is also peculiar in the frequency with which the direction of the slopes of its loops differ.
not always well defined, but always on the side opposite to the other delta.
Accidentals, Fig. 12, as the name im. plies, include patterns which can not be classed under any of the above forms;
It is comparatively uncommon to find the whole ten fingers presenting the same pattern of ridges. Generally there is more than one pattern present. Nevertheless, the number of cases in which loops occur
on all the fingers is considerable, and in these cases the slope, number of ridges between the outer and inner terminuses and the distinctive appearance of the loops, and finally the ridges themselves have to be taken into consideration. In cases where whorls are upon all the fin. gers the varieties of the cores and of the relative dispositions of the ridges with respect to the right delta serve to distinguish them.
Between the digits of the two hands there is, as might be expected, a certain amount of correlation. That is to say, the same patterns occur on the corresponding fingers of the left hand as exists on those of the right, with greater frequency than any other pattern in about the proportion of three to two. The actual degree of correlation between the diferent digits of the same name varies somewhat, but that between the middle fingers is greater than between any of the others.
A matter of much importance respecting these ridges and the patterns they form is whether they are persistent during life or are they liable to vary from any cir. cumstances. Upon this depends their value for purposes of identification. The data at hand for determining the question are not extensive, and several years may have to elapse before it can be conclusively settled. The material available at present for the solution of the problem is mainly that which has been collected by the ener. gies of Mr. Francis Galton, assisted by Sir William J. Herschel and a few other friends. It consists of fifteen cases; in some of these the impressions of only one finger, in others of two fingers, and in a few all the fingers of one hand were avail. able. In all between twenty and thirty digits have been exhaustively studied by Mr. Galton, the impressions of which had been taken at intervals of from nine to thirty-one years. The ages of the persons at the time of taking the first prints ranged from two to sixty-two years, while the second impressions were taken at ages varying from fifteen to seventy-nine. The result of the research was that in every instance there was entire agreement between the various details in each set of prints with one exception. Comparisons made between numerous other double sets of impressions retaken at shorter inter
vals show the same persistence of pattern to prevail. The evidence, therefore, is very strongly in favor of there being no material change or variation in the ridges and furrows of the digits during the life of the individual. Figs. 12 and 13 show im. pressions taken at long intervals, arranged in pairs, for comparison.
In comparing impressions for the purpose of determining the persistence of patterns or whether two sets of impressions are those of the same or of different individuals, the characteristics of the ridges in each print have to be examined with great exactitude. The average num. ber of characteristic points of comparison in an impression of a single finger amount to between thirty and forty. They consist of points of forking and of fusion of ridges, the presence of short, independent ridges at certain given points and of spurs projecting from a ridge, the abrupt termination of a ridge, the appearance of new ridges, and the occurrence of small oval or circular enclosures formed in the course of a ridge by forking and the prongs again immediately reuniting and so walling around depressions that are variously termed craters, lake-basins or islands. Each of these peculiarities has to be exactly localized by counting the ridges from definite points, such as the outer or inner terminus, and by triangulation from these or other fixed prints. In the case of whorls the ridges below the deltas should be traced and their relation to the right delta noted, also the course of the ridges forming the spirals. Allowance must be made, however, for imperfections of printing, thus, for example, a distinct forking of a ridge in one print may appear in another print of the same digit as an imperfect fork, a break in continuity of one or other of the prongs being shown-though generally it is easy to trace some indication of juncture, the important fact to observe being the appearance of a new ridge at the given point, rather than the exact correspondence of detail of minutiæ; again an enclosure or lake basin in one print may appear as a partial enclosure in the other. The scars of incised wounds show a white line, and are attended by dislocation of the continuity of the ridges, whereas crease-lines (which should not be considered, owing to their liability to vary) show break in continuity, but no dislocation of ridges; other scars, such as those of burns, which have injured the true dermis, show actual destruction of the ridges over a larger or smaller area, according to the severity of the injury. Scars from needle pricks, common on the digits of tailors and women, appear as small, irregular white marks in the impressions. In prints of the same person's fingers taken at different intervals discrepancies arising from injuries are likely to be met with, but owing to the many other points of comparison available on parts not affected by the scars do not materially interfere with the work of tracing their similarity, particularly if there are the impressions of several digits available for comparison.
The results of careful comparisons made on many thousands of finger prints have shown up to the present time no two sets of prints of even a single digit have been found to be identically alike, except they were those of the same digit of one and the same individual. It is the case, however, that single digits of different persons have been found to show not only close correspondence in pattern, but also similitude in three or four points of detail in the pattern; the other points have invariably been sufficiently unlike to differentiate eir individuality clearly and with certainty. Finger impressions have, therefore, come to be recognized as a most reliable and easy means of effecting personal identification, and are adopted for this purpose by several police forces for the recognition of old offenders and sometimes for the identification of the perpetrators of crime. Their use might well be extended for the purpose of preventing pensions being drawn by others than the pensioner himself, and indeed for all purposes of identification. When well taken prints of the ten digits of the hands are available for comparison with another set of impressions equally clear, the utmost reliance may be placed upon the evidence they give of the identity or non-identity of the person or persons from whom they were taken,
The impression of one or more fingers may be accidentally made on other substances than paper; it may be on the surface of some object at a place where a
crime has been committed on charge of which some person has been arrested. The question of the identity or non-identity of the print found with the pattern on any of the digits of the prisoner becomes a matter of great importance. The casual print has been made under very different circumstances to those with which it is compared; generally it is the result of a digit somewhat moist with the normal excretions of the skin, plus some dirt superadded, coming in contact with a surface not specially suitable by want of smoothness or otherwise to receive the im. pression, unless the surface happens to be glass, porcelain, or polished metal. The moist condition of the digest may be due to blood upon it, in which case the furrows, as well as the ridges, have probably been covered more or less equally by it. The conditions are, therefore, not as a rule favorable to obtaining good impressions, and it may not be possible to improve them to any extent by dusting powder over them or otherwise. In those cases the greatest caution must be exercised in coming to a conclusion as to the identity of the prints. The affirmative should only be asserted after stringent examination has shown many points in the prints compared to be thoroughly in agreement, and likewise the absence of any obvious disagreement between them. The latter condition is as essential as the former, while the presence of any disagreement should be regarded as distinct evidence that the prints were made by different fingers. A question of some importance is whether any discrepancy will be produced in two prints of the same fin. ger by reason of their being made under different degrees of pressure. Minor vari. ations, such as those which depend on dif. ferences in height of the ridges, do occur in the prints as a result of the finger being lightly or heavily pressed in printing; in the latter case a ridge may appear continuous, which in the former case shows interruption in continuity, but irregularity in inking the finger will produce the same effect. Heavy pressure flattens the ridges somewhat, and therefore makes them appear broader in the print, but again this condition is to some extent at least inseparable from the manner of inking the fin. gers, for if only the summits of the ridges