Note 191 — Chapter IV · MEXICAN HIEROGLYPHICS—MANUSCRIPTS—ARITHMETIC—CHRONOLOGY—ASTRONOMY

In this calendar, the months of the tropical year were distributed into cycles of thirteen days, which, being repeated twenty times,—the number of days in a solar month,—completed the lunar, or astrological, year of 260 days; when the reckoning began again. “By the contrivance of these trecenas (terms of thirteen days) and the cycle of fifty-two years,” says Gama, “they formed a luni-solar period, most exact for astronomical purposes.” (Descripcion, Parte 1, p. 27.) He adds that these trecenas were suggested by the periods in which the moon is visible before and after conjunction. (Loc. cit.) It seems hardly possible that a people capable of constructing a calendar so accurately on the true principles of solar time should so grossly err as to suppose that in this reckoning they really “represented the daily revolutions of the moon.” “The whole Eastern world,” says the learned Niebuhr, “has followed the moon in its calendar; the free scientific division of a vast portion of time is peculiar to the West. Connected with the West is that primeval extinct world which we call the New.” History of Rome, vol. i. p. 239.