We have thought it proper and interesting to preface the description of the calendar stone by the preceding account of the Aztec festival of the New Fire, which illustrates the mingled elements of science and superstition that so largely characterized the empire of Montezuma. The stone itself has engaged the attention, for years, of numerous antiquarians in Mexico, Europe and America, but it has received from none so perfect a description, as from the late Albert Gallatin, who devoted a large portion of his declining years to the study of the ancient Mexican chronology and languages. In the first volume of the Transactions of the American Ethnological Society he has contributed an admirable summary of his investigations of the semi-civilized nations of Mexico, Yucatan and Central America, and from this we shall condense the portion which relates to this remarkable monument. Around the principal central figure, representing the sun, are delineated in a circular form the twenty days of the month; which are marked from 1 to 20, with figures in the plates, and, in this order, are the following: 1 Cipactli. 2 Xochitl. 3 Quiahuitl. 4 Tecpatl. 5 Ollin. 6 Cozcaquauhitli. 7 Quauhtli. 8 Ocelotl. 9 Acatl. 10 Malinalli. 11 Ozomatli. 12 Itzeuinitli. 13 Atl. 14 Tochtli. 15 Mazatl. 16 Miquiztli. 17 Cohualt. 18 Cuetzpalni. 19 Calli. 20 Ehecatl. The triangular figure I, above the circle enclosing the emblem of the sun, denotes the beginning of the year. Around the circumference which bounds the symbols of the days and months are found the places of fifty-two small squares, of which only forty are actually visible, the other twelve being covered by the four _principal_ rays of the sun marked R. These doubtless denote the cycle of 52 years; and each of these squares contains five small oblongs, making in all 260 for the 52 squares. They are presumed to represent the 260 days or the period of the twenty first series of thirteen days. All the portion, included between the outer circumference of these 260 days and the external zone, has not been decyphered accurately. The external zone consists, except at the extremities, of a symbol twenty times repeated, and is alleged by Gama, a Mexican who first described and attempted to interpret the stone, to represent the milky way. The waving lines connected with it are supposed by this writer to represent clouds, while others imagine them to be the symbols of the mountains in which clouds and storms originated. These fanciful interpretations, however, are unavailable in all scientific descriptions, and Mr. Gallatin supposes the figures to be altogether ornamental.