The Mexican archæologist, Leony Gama, considers the stone not only to be a calendar, but a solar clock, which by means of shadows cast in a certain manner gave eight intervals of the day between the rising and setting sun. He adds that the stone clearly shows the dates of the vernal and autumnal equinoxes, summer and winter solstice. On the other hand, the antiquarian Chavero is of opinion that the stone could not have been used as a calendar on account of lacking certain indispensable elements for the computation of time. He considers it a gigantic votive monument to the sun, above which sacrifices were offered. Whatever was the original intention of the sculptures of this great stone, it has survived them to bear testimony to their attentive notice of the movements of the earth and heavenly bodies, of their interest in astronomy, and their accuracy in arithmetical calculation, as well as their skill in carving and design, and their power to overcome the mechanical difficulty of moving so huge a mass of stone. The cycle of the Aztecs was a period of fifty-two years. They believed that some great catastrophe would occur at the end of one of these cycles, and therefore approached the termination of each one, at the interval of fifty-two years, with terror and dismay. On the arrival of the five unlucky days at the close of the year when the end of the cycle recurred, they abandoned themselves to despair. They broke in pieces the little images of their household gods, lighted no fires in their dwellings, and allowed the holy fires in the temples to burn out. They destroyed every thing they possessed, and tore their garments, as if there was to be no further use for earthly comforts. On the evening of the fifth day a procession moved from the city to the top of a hill six miles south of the city. There, at midnight, just as the constellation of the Pleiades reached the zenith, a new fire was kindled by rubbing sticks over the breast of a human victim. The body of this victim was thrown to the flames which sprang up from the new-born fire. Shouts of joy and delight burst forth from the surrounding hills, the housetops, and terraces, which were crowded with the populace watching for the result. Torches lighted at the blazing pile were carried to every home, and kindled with fresh flame every hearthstone. The sun rose, the new cycle commenced, and the Aztecs felt safe for fifty-two years more. Then came the house-cleaning. All the destroyed pots and pans were replaced by new ones. New clothes, prepared, we must fear, beforehand, took the place of the old ones. The people, gayly dressed and crowned with flowers, thronged to the temples to offer up their thanksgiving. All was joy and merriment; dances and songs were the order of the day, gifts exchanged. The last celebration of this festival was in 1506.