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 institutions 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 identity 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:--