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APPENDIXr 



teen days after the end of fifty-two years became fuper- 

 fluous, or without the retroceffion of a day every four 

 years, the difference of the folar year, at the end of the 

 cycle fliould have been double, that is twenty-fix days. 



We wonder much that an author, who appears to be 

 a good calculator, fliould err in a calculation fo fimple 

 and clear. The year 1506, was a fecular year among 

 the Mexicans. Let us fuppofe for the fake of perfpi- 

 cuity, that their year began as ours on the firft day of 

 January. This firfl year of the Mexican century, com- 

 pofed like ours of 365 days, ended as ours on the 31(1 

 of December, and in like manner the fecond year corref- 

 ponding to 1507 ; but in 1508, the Mexican year ought 

 to finifli a day before ours ; becaufe ours being bifTextile, 

 or leap year, had 366 days, whereas the Mexican had 

 only 365 ; therefore the fourth year of the Mexican 

 century correfponding to 1509, ought to commence a 

 day before ours, that is on the 31ft of December 1 508. 

 In the fame manner, the eighth year, correfponding to 

 1513, ought to commence on the 30th of December, 

 151 2, for the fame reafon of that year having been bif- 

 fextile. The twelfth year, correfponding to 1517, ought 

 to begin on the 29th of December 15 16, and fo forth, 

 unto the year 1557, the lafl: of the Mexican century, m 

 which the Mexican year ought to anticipate ours as ma- 

 ny days as there were biffextile years. Thus in the 52 

 years of the Mexican century, there are thirteen biffex- 

 tile ; the laft year of the century, therefore, ought to 

 anticipate ours by thirteen days, and not twenty-fix. 

 Confequently, the interpofition of the thirteen days to 

 adjufl the year at the end of the century with the courfe 

 of the fun was not fuperfluous. So that Gemelli faid 

 properly as to the anticipation of the day, although he 



erred 



