56 L. Ideler, _op. cit._ i. 149-152. Macrobius thought that the Egyptians had always employed a solar year of 365-¼ days (_Saturn._ i. 12. 2, i. 14. 3). The ancient calendar of the Mexicans resembled that of the Egyptians except that it was divided into eighteen months of twenty days each (instead of twelve months of thirty days each), with five supplementary days added at the end of the year. These supplementary days (_nemontemi_) were deemed unlucky: nothing was done on them: they were dedicated to no deity; and persons born on them were considered unfortunate. See B. de Sahagun, _Histoire générale des choses de la Nouvelle-Espagne_, traduite par D. Jourdanet et R. Simeon (Paris, 1880), pp. 50, 164; F. S. Clavigero, _History of Mexico_ (London, 1807), i. 290. Unlike the Egyptian calendar, however, the Mexican appears to have been regularly corrected by intercalation so as to bring it into harmony with the solar year. But as to the mode of intercalation our authorities differ. According to the positive statement of Sahagun, one of the earliest and best authorities, the Mexicans corrected the deficiency of their year by intercalating one day in every fourth year, which is precisely the correction adopted in the Alexandrian and the Julian calendar. See B. de Sahagun, _op. cit._ pp. 286 _sq._, where he expressly asserts the falsehood of the view that the bissextile year was unknown to the Mexicans. This weighty statement is confirmed by the practice of the Indians of Yucatan. Like the Aztecs, they reckoned a year to consist of 360 days divided into 18 months of 20 days each, with 5 days added so as to make a total of 365 days, but every fourth year they intercalated a day so as to make a total of 366 days. See Diego de Landa, _Relation des choses de Yucatan_ (Paris, 1864), pp. 202 _sqq._ On the other hand the historian Clavigero, who lived in the eighteenth century, but used earlier authorities, tells us that the Mexicans “did not interpose a day every four years, but thirteen days (making use here even of this favourite number) every fifty-two years; which produces the same regulation of time” (_History of Mexico_, Second Edition, London, 1807, vol. i. p. 293). However, the view that the Mexicans corrected their year by intercalation is rejected by Professor E. Seler. See his “Mexican Chronology,” in _Bulletin 28_ of the Bureau of American Ethnology (Washington, 1904), pp. 13 _sqq._; and on the other side Miss Zelia Nuttall, “The Periodical Adjustments of the Ancient Mexican Calendar,” _American Anthropologist_, N.S. vi. (1904) pp. 486-500. M25 In Egypt the operations of husbandry are dependent on the annual rise and fall of the Nile.