Humanum longe praesentit odorem Romulidarum acris servator, candidus anser. Birds of prey will scent the battle-field at prodigious distances, and they are often seen hovering instinctively over the ground where the conflict is to supply their festival. Humboldt relates, that in Peru, at Quito, and in the province of Popayan, when sportsmen wish to obtain that species of vulture called _vultur gryphus_, they kill a cow or a horse, and in a short time these sagacious birds crowd to glut their ravenous appetites. Ancient historians assert that vultures have cleft the air one hundred and sixty-six leagues to arrive in time to feast upon a battle; and Pliny boldly affirms that even crows have so acute a sense of approaching corruption, that they can scent death three days before dissolution, and generally pay the _moribond_ a visit a day before his time, not to be disappointed. This notion has become a vulgar prejudice, as much so, indeed, as the howling of a dog, which is considered in most countries as foreboding death. In various animals an offensive odour is a protective gift. The _staphylinus olens_, for instance, sheds an effluvium which effectually keeps away the birds who would otherwise pounce upon him. But of all singular perfections in the sense of smelling that were ever recorded, may be cited the monk of Prague and the blind man in the Quinze-vingt Hospital of Paris, who possessed the faculty of ascertaining the presence of virginity whenever a female had the luck of being introduced to them. Many curious instances are recorded, where the loss of one sense has added to the acuteness of others. Dr. Moyse the well-known blind philosopher, could distinguish a black dress on his friends by the smell. Professor Upham of the United States, mentions a blind girl who could select her own articles out of a basket of linen brought in by the laundress. These anomalous senses, for such they may be called, are as wonderful as they are inexplicable, and appear to arise from a peculiar sensibility of the organs of smell, which renders them capable of being stimulated in a peculiar manner, that no language can express or define. It is scent, no doubt, that gives the migratory power to various animals; "which enables them," to use the words of Dr. Mason Good, "to steer from climate to climate, and from coast to coast; and which, if possessed by man, might perhaps render superfluous the use of the magnet, and considerably infringe upon the science of logarithms? Whence comes it that the fieldfare and red-wing, that pass the summer in Norway, or the wild-duck and merganser, that in like manner summer in the woods and lakes of Lapland, are able to track the pathless void of the atmosphere with the utmost nicety, and arrive on our own coasts uniformly in the beginning of October."[11]