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Naxium, Emery

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NAXIUM.
249
bow, in order to work so evenly, and not to run the risk of split­ting the cylinder. It could not have been long before the en­gravers discovered that the same principle applied by means of blunt points varying in thickness would enable them to sink almost the whole of their design with extreme accuracy, only requiring a slight finish from the cutting medium. Hence many of the neater Babylonian class exhibit in their mode of execution as extensive, or rather exclusive, employment of the drill, as marks the largest proportion of the Etruscan scarabsei, which still retain the stamp of their Asiatic origin in their manufacture, though not in their subjects.
It must be here explained, that the metal point takes no part in cutting the stone, but merely serves as a medium in which the acuter particles of the pounded Corundum embed themselves, and bring an infinite number of cutting surfaces, continually renewed, to bear upon the stone. The softer the metal the larger proportion of these cutting particles does it take up and carry ; hence a bronze drill will work faster than one of steel. The modern gem-engraver sets all his drills and cutting tools, how­ever differently shaped, to work, by making them revolve hori­zontally by means of a lathe driven by the foot whilst he presses the gem cemented into a handle against the cutting edge. These cutters are, as they are wanted, fixed in a spindle driven by the wheel, whence the name of the entire contrivance. On the con­trary, the ancient engraver, reversing the operation, brought his drills to bear upon a fixed surface, and turned them merely by means of the bow moved by his right hand, whilst he directed the drill with the left. Thus only is it possible to understand how the ancients were enabled to work out those enormous camei, the extent of which presents difficulties insuperable by the modem process. More than one artist could thus have laboured simultaneously upon the same slab of sardonyx, the simple drill and bow requiring so little room for their application. Indeed every really antique cameo shows distinctly how the superfluous parts of the upper stratum have been excised by means of cir­cular perforations.
Sir G. Wilkinson is also of opinion that the Egyptians per­formed their stupendous sculptures in basalt, granite, and other
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