To return, however, to the flakes of flint which were used in this country for scraping or cutting purposes, at an early period, when metal was either unknown or comparatively scarce. Each flake, when dexterously made, has on either side a cutting edge, so sharp that it almost might, like the obsidian flakes of Mexico, be used as a razor. Some flakes indeed seem to have served as surgical instruments, as the practice of trephining was known in the Stone Period. So long as the edge is used merely for cutting soft substances it may remain for some time comparatively uninjured, and even if slightly jagged its cutting power is not impaired. If long in use, the sides of the blade become rather polished by wear, and I have specimens, both English and foreign, on which the polish thus produced can be observed. If the flake has been used for scraping a surface, say, for instance, of bone or wood, the edge will be found to wear away, by extremely minute portions chipping off nearly at right angles to the scraping edge, and with the lines of fracture running back from it. The coarseness of these minute chips will vary in accordance with the amount of pressure used, and the material scraped; but generally speaking, I think that I am right in saying that they are more delicate and at a more obtuse angle to the face, than the small chipping produced by the secondary working of the edge of a flake, of which I shall presently speak. In all cases where any considerable number of flakes of flint occur, such as there appears to be good reason for attributing to a remote period, a greater or less proportion of them will, on examination, be found to bear these signs of wear upon them, extending over, at all events, some portion of their edges. |290| It is, however, difficult if not impossible, always to determine whether the chipping away of the edge of a flake is merely the result of use, or whether it is intentional. There can be no doubt that for many purposes the acute edge of a flake, as originally formed, was too delicate and brittle, and that it was therefore re-worked by subsequent chipping, so as to make the angle more obtuse, and thus strengthen the edge of the tool. It is curious to observe how rarely the edges of flakes were sharpened by grinding. It was probably considered less troublesome to form a new flake than to sharpen an old one; in the same way as it is recorded that the Mexican barbers threw away their obsidian flakes as soon as they were dull and made use of new ones. Dr. E. B. Tylor, in the free translation of the passage in Torquemada relating to these razors, appears, as has been pointed out by Messrs. Daubrée and Roulin,[1301] to have fallen into a mistake in representing them to have been sharpened on a hone, the original author having merely said that the edge of the obsidian flakes was as keen as if they had been forged in iron, ground on a stone, and finished on a hone. * * * * *