There are, moreover, a certain number of small cores, or nuclei, both English and foreign, from which such minute and regular flakes have been detached, that it is difficult to believe that a mere stone hammer could have been directed with sufficient skill and precision to produce such extreme regularity of form. I may cite as instances some of the small nuclei which are found on the Yorkshire wolds, and some of those from the banks of the Mahanuddy,[88] in India, which, but for the slight dissimilarity in the material (the latter being usually chalcedony and the former flint), could hardly be distinguished from each other. Possibly in striking off the flakes some form of punch was used which was struck with the hammer as subsequently described. There are also some large nuclei, such as those from the neighbourhood of the Indus,[89] in Upper Scinde, and one which I possess from Ghlin, in Belgium, which are suggestive of the same difficulty. In form they much resemble the obsidian cores of Mexico, and it seems not improbable that they are the result of some similar process of making flakes or knives to that which was in use among the Aztecs. Torquemada[90] thus describes the process he found in use:—“One of these Indian workmen sits down upon the ground, and takes a piece of this black stone” (obsidian) “about eight inches long or rather more, and as thick as one’s leg or rather less, and cylindrical; they have a stick as large as the shaft of a lance, and three cubits or rather more in length; and at the end of it they fasten firmly another piece of wood, eight inches long, to give more weight to this part; then, pressing their naked feet together, they hold the stone as with a pair of pincers or the vice of a carpenter’s bench. They take the stick (which is cut off smooth at the end) with both hands, and set it well home against the edge of the front of the stone (_y ponenlo avesar con el canto de la frente de la piedra_), which also is cut smooth in that part; and then they press it against their breast, and with the force of the pressure there flies off a knife, with its point, and edge on each side, as neatly as if one were to make them of a turnip with a sharp knife, |24| or of iron in the fire.” Hernandez[91] gives a similar account of the process, but compares the wooden instrument used to a cross-bow, so that it would appear to have had a crutch-shaped end to rest against the breast. So skilful were the Mexicans in the manufacture of obsidian knives, that, according to Clavigero, a single workman could produce a hundred per hour.