provide a general register of all known criminals in the country. [Illustration: EAR AND HEAD MEASURERS (THE BERTILLON SYSTEM).] [Illustration: MR. GALTON'S TYPES OF FINGER-PRINTS.] The ineffaceable odour of musk and other strong scents has more than once brought home robbery and murder to their perpetrators. A most interesting case is recorded by General Harvey,[1] where, in the plunder of a native banker and pawnbroker in India, an entire pod of musk, just as it had been excised from the deer, was carried off with a number of valuables. Musk is a costly commodity, for it is rare, and obtained generally from far-off Thibet. The police, in following up the dacoits, invaded their _tanda_, or encampment, and were at once conscious of an unmistakable and overpowering smell of musk, [Illustration: "AFTER A SHORT STRUGGLE ... THE THIEVES SEIZED THE OPIUM" (p. 18).] which was presently dug up with a number of rupees, coins of an uncommon currency. In another instance a scent merchant's agent, returning from Calcutta, brought back with him a flask of spikenard. He travelled up country by boat part of the way, then landed to complete the journey, and carried with him the spikenard. He fell among thieves, a small gang of professional poisoners, who disposed of him, killing him and his companions and throwing them into the river. Long afterwards the criminals, who had appropriated all their goods, were detected by the tell-tale smell of the spikenard in their house, and the flask, nearly emptied, was discovered beneath a stack of fuel in a small room. Yet again, the smell of opium led to the detection of a robbery in the Punjaub, where a train of bullock carts laden with the drug was plundered by dacoits. After a short struggle the bullock drivers bolted, the thieves seized the opium and buried it. But, returning through a village, they were intercepted as suspicious characters, and it was found that their clothes smelt strongly of opium. Then their footsteps were traced back to where they had committed the robbery, and thence to a spot in the dry bed of a river, in which the opium was found buried. In India, again, many cases of obscure homicide have been brought to light by such a trifling fact as the practice, common among native women, of wearing glass, or rather shell lac, bangles or bracelets. These _choorees_, as they are called, are heated, then wound round wrist or ankle in continuous circles and joined. They are very brittle, and will naturally be easily smashed in a violent struggle. Fruitless search was made for a woman who had disappeared from a village, until in a field adjoining the fragments of broken _choorees_ were picked up. On digging below, the corpse of the missing woman, bearing marks of foul play, was discovered.