Page:Popular Science Monthly Volume 31.djvu/547

Rh It may be asked, however, how came their temples, and such works as the so-called Calendar Stone, for instance, so exquisitely carved, if they knew not the use of bronze? As for their temples, Mr. Norman has told us that most of them are composed of a fine concrete limestone, in the carving of which "flint was undoubtedly used." Only implements of flint, obsidian, and other stones, and copper have been found among these ruins, and this fact rather encourages the belief that the natives carved these stones when first taken from the quarry, in their soft condition, with tools of this description, the rock afterward becoming hard on exposure to the air. Herrera, speaking of the districts of Yucatan, distinctly tells us that "in all of them there were so many and such stately stone buildings, that it was amazing, and the greatest wonder is that, having no use of any metal, they were able to raise such structures." Landa, too, who was a contemporary of the conquest, adds his testimony by saying that "there exist many beautiful structures of masonry in Yucatan, all of them built of stone, and showing the finest workmanship, the most astonishing that ever were discovered in the Indies, and we can not wonder at it enough, because there is not any class of metal in this country by which such works could be accomplished."

The so-called Calendar and Sacrificial Stones unearthed in the city of Mexico, and most of their idols, are made from large blocks of basalt, and to dress or carve this very hard volcanic material with a bronze chisel, however well it may be tempered, is impossible. A process of grinding and rubbing, which archæologists have now demonstrated to be extremely practicable, and in which the Mexicans, as in other things, became more expert than their northern brethren, was doubtless the only means employed.

The remains of native work in bas relief are now known to be very numerous, but neither among the ruins of Palenque, Uxmal, Copan, Chichen, nor Mitla can there be found a single metal tool. Had these extensive works been fashioned with bronze implements, far more specimens than the paltry three that we have would have come to light ere now, within the broad area in which they are embraced.

reviews the subject of elective studies in his annual report of Columbia College. He thinks that during the growing period of the mind the studies should be prescribed, for discipline, and to discover the bent of the mind. They should, at the same time, be so varied as to offer every faculty of the mind an equal inducement for exertion. The preference will then be free to manifest itself. The time for introducing the elective element should be fixed, then, rather with reference to maturity of years than to the degree of advancement in the four years' round of college study. This, with the average of college students, appears to be attained in the nineteenth or twentieth year; an age which corresponds, in most students, nearly with the end of the sophomore year.