540 LECTURE XLIV. 



small a difference can be of no material consequence. The Persians had in- 

 troduced into their calendar, in the 1 1th century, an intercalation still more 

 accurate; they make 8 bissextiles only every 33 years, reckoning four common 

 years together instead of three, at the end of this period, so that in 13'i years 

 they have 32 leap years instead of 33 ; and the error is only a day in about five 

 thousand years. If any change in the Gregorian calendar were thought 

 necessary, it would be easy to make the last year of every fourth and fifth 

 century alternately a bissextile, and this correction would be quite as accu- 

 rate as it is possible for our calculations to render it. The adoption bf the 

 Gregorian calendar in this country was for some time delayed by religious 

 prejudices; one of the best founded objections to it was, that 2 days of the 

 real error was still uncorrected ; but better arguments at last overcame these 

 difficulties, and the new stile was introduced on the 14 September 1754, 

 "which would have been called, according to the old stile, the third. 



Any tolerable approximation of this kind, when once generally established, 

 appears to be more eligible than the mode which was lately adopted in France, 

 where the republican year began at the instant of the midnight preceding 

 the sun's arrival at the autumnal equinox. Mr. Lalande very judiciously 

 observes, that there are several years, in which the sun will pass the equinox 

 so near to midnight, that it is not at present in the.power of calculation to 

 determine on what day the republican year ought to begin; and perhaps 

 these arguments have cooperated with others in facilitating the restoration of 

 the ancient calendar. 



The revolutions of the sun and moon are not very obviously commen- 

 surable, the solar year containing 12 lunations and almost 11 days; but 

 Meto discovered, more than 2000 years ago, that 19 solar j'ears contain 

 exactly 235 lunations; and this determination is so accurate, that it makes 

 the lunar month only about half a minute too long. Hence it happens, that 

 in every period of 19 years, the moon's age is the same on the same day of 

 the year. The number of the year, in the Metonic cycle, is called the golden 

 number, the calendar of Meto having been ordered, at the celebration of 

 the Olympic games, to be engraved in letters of gold on a pillar of marble. 

 At present, if we add 1 to the number of the year, and divide it by 19, the 

 remainder will be the golden number; thus, for 1806, the golden number is 2. 



