391 
ages should employ a very imperfect mode of 
intercalation^ might nevertheless maintain har- 
mony between its calendar, and that of the most 
civilized people, if, led by direct observation of 
the heavenly bodies, it changed at times the begin ^ 
ning of its year. The Mexican history, in its 
annals, offers no trace of such sudden changes, 
or extraordinary intercalations. Since the ce- 
lebrated epoch of the sacrifice of Tlaiixco, the 
calendar had undergone no reform, the interca- 
lation was uniformly made at the end of each 
cycle ; and to explain how four centuries had 
not been sufficient to produce a perceptible error 
in the chronology, Mr. Gama admits, that the 
Mexicans intercalated only twenty-five days 
every cycle of a hundred and four years, cehue- 
huetiliztli, or twelve days and a half at the end 
of each cycle of fifty-two years, which fixes the 
duration of the year to 365*24 days. He thinks 
himself enabled to conclude from the statement 
even of the historians of the sixteenth century, 
that the secular festival was celebrated day and 
night alternately ; and that, if the years of a 
cycle began all at midnight, those of another be- 
gan all at noon. Unable to examine the works 
written in the Mexican language, I cannot de- 
cide on the contrary of Mr. Gama’s opinions. 
The reasons which he alleges in his dissertation 
on the monuments discovered in 1790, appear to 
me less conclusive, since I have been enabled to 
