solemn occasions. I have but little hesitation in asserting that the groove in the upper surface formed no part of the original design.
It has been surmised that this is the "exceedingly great stone" which was discovered by the Mexicans as late as the reign of Montezuma, when it is recorded that it was brought to the capital with great labour and pomp for the sacrifices: on which occasion 12,210 victims were immolated.
It may fairly be credited that many of these antiquities were the work of a people anterior to the Aztecs.
No doubt can be entertained but that their systems for the computation of time were transmitted to them from the Toltecs.
The great Calendar Stone is a vast mass of basaltic porphyry, twenty-four tons weight, covered with the most symmetrical and admirable hieroglyphics.
Two several calendars were in use among the aborigines, namely: the Reckoning of the Sun, used for civil purposes, and the Calendar of the Moon, employed to regulate their religious festivals.[1]
The Reckoning of the Sun was briefly as follows.[2] The civil year consisted of three hundred and sixty four days, divided into eighteen months of twenty days each, with exception of the last, to which the five odd days were added. But evidently knowing that the tropical year exceeded their year by six hours, they, after the termination of each cycle of fifty-two years, added thirteen days before they recommenced the first month of the following cycle, and thus adjusted their time. Each of the eighteen months has a certain name from some natural object characteristic of the particular season which it indicated, or from some particular festival or employment in which they were engaged at
