The Aztecs divided their cycle of fifty two years, into four periods of thirteen years; called TLALPILLI, and their month of twenty days, into four sub-periods, or weeks, of five days. The cycle was called XIUHMOLPILLI, which signifies, "the tying up of years." Each day of the month had a separate _name_, derived from some animate, or inanimate object, as _Tochtli_, a rabbit, _Calli_, a house, _Atl_, water, _Tecpatl_, Silex, _Xochitl_, a flower, _Cohuatl_, a serpent. The fifth day, was a fair or market day. The names of the days were represented by hieroglyphic figures of the objects described. The divisions were perfect and regular, and enabled them to denote, in their scrolls of picture writing, the chronology of the month, and of the Tlalpilli, or period of thirteen years.[10] [10] As to the market day or week of five days, Sir Wm. Jones and Sir Stamford Raffles, tell us that the same period, existed, for the same purpose, in India. In the symbols for days, we find four to correspond exactly with the zodiacal signs of India, eight with those of Thibet, six with those of Siam and Japan, and others with those of the Chinese and Moguls. The scheme itself denotes, not only a very certain mode of keeping the record of time, but a very exact knowledge of the tropical year. It is now known that the length of the year is precisely three hundred and sixty five days, five hours, forty eight minutes, and forty eight seconds; and it is perfectly well ascertained, that the Aztecs computed its length, at the period of their highest advance, at three hundred and sixty five days, five hours, forty six minutes, and nine seconds, differing only two minutes and thirty nine seconds from our own computation.[11] There is evidence, indeed, that the ancient inhabitants of this continent, had more science, than is generally conceded. If we are to credit writers, the Aztecs understood the true causes of eclipses, as well as we do. Diagrams exist, in their pictorial records, in which the earth is represented as projecting its disc upon the moon--thus indicating, clearly, a true knowledge of this phenomenon. Mr. Gallatin remarks that the Indian astronomical system, as developed in Mexico, is not one of _indigenous origin_, but that they had, manifestly, received it, at least their calendar, from a foreign source. Its results could not have been attained without long and patient observations. Some of its methods of combination, in the double use of names and figures, in their cycles, are thought to denote an ancient primitive system of oriental astronomy, reaching back to the earliest times. Here, then, we have one probable fact to serve as the nucleus of antiquarian testimony. We begin it abroad.