Aztec Civilisation
days, or rather twelve and a half, this being the number which had fallen in arrear. Had they inserted thirteen, it would have been too much, since the annual excess over three hundred and sixty-five is about eleven minutes less than six hours. But, as their calendar, at the time of the Conquest, was found to correspond with the European (making allowance for the subsequent Gregorian reform), they would seem to have adopted the shorter period of twelve days and a half,1 which brought them, within an almost inappreciable fraction, to the exact length of the tropical year, as established by the most accurate observations.2 Indeed, the intercalation of twenty-five days, in every hundred and four years, shows a nicer adjustment of civil to solar time than is presented by any European calendar; since more than five centuries must elapse, before the loss of an entire day.3 Such was the astonishing precision displayed by the Aztecs, or, perhaps, by their more polished Toltec predecessors, in these computations, so difficult as to have baffled, till a comparatively recent period, the most enlightened nations of Christendom!4
The chronological system of the Mexicans, by which they determined the date of any particular event, was also very remarkable. The epoch, from which they reckoned, corresponded with the year 1091, of the Christian era. It was the period of the reform of their calendar, soon after their migration from Aztlan. They threw the years, as already noticed, into great cycles, of fifty-two each, which they called "sheafs," or "bundles," and represented by a quantity of reeds bound together by a string. As often as this hieroglyphic occurs in their maps, it shows the number of half centuries. To enable them to specify any particular year, they divided the great cycle into four smaller cycles, or indictions, of thirteen years each. They then adopted two periodical series of signs, one consisting of their numerical dots up to thirteen, the other, of four hieroglyphics of the years.5 These latter they repeated in regular succession, setting against each one a number of the corresponding series of dots, continued also in regular succession up to thirteen. The same system was pursued through the four indications, which thus, it will be observed, began always with a different hieroglyphic of the year from the preceding; and in this way, each of the hieroglyphics was made to combine successively with each of the numerical signs, but never twice with the same; since four, and thirteen, the factors of fifty-two,—the number of years in the cycle,—must admit
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