That they should have accomplished these difficult works with such tools as they possessed, is truly wonderful. It was comparativeIy easy to cast and even sculpture metallic substances, both of which they did with consummate skill. But that they should have shown the like facility in cutting the hardest substances, as emeralds and other precious stones, is not easy to explain. Emeralds they obtained in considerable quantity from the barren district of Atacames, and this inflexible material seems to have been almost as ductile in the hands of the Peruvian artist as if it had been made of clay.17 Yet the natives were unacquainted with the use of iron, though the soil was largely impregnated with it.18 The tools used were of stone, or more frequently of copper. But the material on which they relied for the execution of their most difficult tasks was formed by combining a very small portion of tin with copper.19 This composition gave a hardness to the metal which seems to have been little inferior to that of steel. With the aid of it, not only did the Peruvian artisan hew into shape porphyry and granite, but by his patient industry accomplished works which the European would not have ventured to undertake. Among the remains of the monuments of Cannar may be seen movable rings in the muzzles of animals, all nicely sculptured of one entire block of granite.20 It is worthy of remark, that the Egyptians, the Mexicans, and the Peruvians, in their progress towards civilization, should never have detected the use of iron, which lay around them in abundance; and that they should each, without any knowledge of the other, have found a substitute for it in such a curious composition of metals as gave to their tools almost the temper of steel; 21 a secret that has been lost--or, to speak more correctly, has never been discovered-by the civilized European.