The disease called Acromegaly, or giant growth, involves great expansion of the ridges and furrows, but no case of actual change of patterns has been observed as yet. The attention of medical men should be given to this affection in regard to modification of linear arrangement.
The likeness or divergence of finger-patterns in neighbouring supernumerary fingers and toes might yield interesting results if carefully recorded. Extra fingers are commoner than extra toes. The webbing of fingers, as in the chimpanzee, might also be noticed, and any association with retrograde patterns, in the fingers concerned.
The rapid growth of a literature of Criminology is partly the result of better methods of identification. It is unscientific to reason about the personal peculiarities of all the Toms, Dicks, and Harrys, when Tom may be Dick, or Dick Harry under a different alias. The criminologist can now use his prison statistics as to age, habits, and the like, with much greater confidence and precision. In an interesting, but somewhat reckless work on “Criminal Man,” which summarizes the teaching of the eminent Italian authority on the anatomy and psychology of the criminal—of the Italian criminal at least—Cesare Lombroso, we are told (p. 20): “Long fingers are common to swindlers, thieves, sexual offenders, and pickpockets. The lines on the palmar surfaces of the finger-tips are often of a simple nature, as in the anthropoids.” But they are not, necessarily, of a simple nature in the anthropoids, but often highly ornate and complex in their ramifications. In the lower monkeys they are much simpler, and Sir F. Galton thought it was so sometimes in the negro peoples. Indeed, one is not surprised to meet such simple lineation patterns now and again in cultivated people, without any criminal taint, or negro blood, or any anti-socialistic tendencies that can be easily detected. A cautious prison doctor in Glasgow, Dr. Devon, has written a clever book which gives much food for sober reflection. He seems to say that the criminal is not a kind of species by himself: “If those who come to prison for the first time were made the subject of examination, it would be found that they are principally remarkable for the absence of what the books call criminal characteristics.” (p. 11.)
CHAPTER V
TECHNIQUE OF PRINTING AND SCRUTINIZING FINGER-PATTERNS
There are important points connected, with the printing of finger-patterns, especially for legal investigation, which come now to be considered. A human finger, as we have seen, is not, for printing purposes, just like a lithographic stone, a box-wood engraving, or a plate of zinc, steel, or copper. In ordinary printing, especially of high-class and delicate engravings, the quality and fluency of ink, the smoothness of surface and hygrometric conditions of paper—due sometimes to local atmosphere, and sometimes to climate generally—the skill of workmen, all the conditions co-operate in producing variations, slight it may be, but noticeable in the results obtained. In the case of finger-prints we might also have to consider the willingness or unwillingness of the subject having his finger-prints officially taken. A finger—even that of a dead person—is compressible, while retaining on the whole the pattern of its furrows and ridges, and hence under fairly similar conditions, the printed products may be somewhat different in appearance. The same fact would apply, no doubt, also to impressions taken from an indiarubber stamp, made, we shall suppose, for stamping purposes in regard to documents, in imitation of a particular finger-print pattern. Greater compression tends to flatten out the ridges and to narrow the intervening grooves, while it may also tend, especially when associated with over-inking, to obliterate some of the characteristic ramifications of the pattern. But, again, the finger of a living person is usually in a state of physiological activity. It swells or shrinks, drying up or exuding moisture from its many pores, which facts, however minute and insignificant they may appear to the uninstructed, to the trained dactylographer they leave a most interesting and significant record behind.
Examine carefully a ridge which has been printed—and, if possible, photographically enlarged—at various periods not long apart, and the pores with which it is dotted will be found, while retaining their relative positions, to vary somewhat in their degree of patency. A single ridge might be compared to a naval cruiser, the numerous funnels of which are not all belching forth smoke at the same time, but one is almost smokeless while its neighbour is quite active. Those pores which have been copiously emitting sweat are seen, when imprinted, to be larger than those that were inactive. An imaginary case was once suggested to me as a final blow to finger-print identification. A certain Mr. William Sykes is officially known to be recruiting his valuable health at one of His Majesty’s sanatoriums for people of his profession. That celebrated artist’s “thumb”-print, however, has been found liberally spotted all over the scene of some tragic area of crime. What is to be said? Well, the prodigality of display of the well-known sign-manual, in circumstances when gloves are almost invariably now worn by experts, might well arouse suspicion in itself, but it would easily be found in such a case that the pattern had been prodigally repeated with too great fidelity in the matter of sweat-pores, which, in the case of an active burglar, who is a sober, hard-working fellow in spite of his faults, would vary with each successive imprint, in a way that no manufacturer of bogus “thumb”-prints could easily follow.
The fact that a finger—a clean finger—is naturally, to some slight extent, greasy, partly from sebaceous secretion, enables the expert dactylographer by various chemical and mechanical means to obtain a pretty clear vision, even in minute detail, of what before had been quite invisible. A mere accidental smudge from a slightly oily palm or finger, if imprinted on glass, japanned tin, varnished or polished wood, etc., may have its invisible lineations brought out by dusting gently upon it some light powder of appropriate colour. Dr. René Forgeot, in 1891, first called attention to this method of bringing out latent imprints, and my friend, Dr. Garson, of this country, gave it further developments.