used by the Ancient Egyptians. 187 



singular accuracy, being nearly equal to 7421 synodical revolutions of the moon. 

 In fact, if we assume 600 tropical years to be equal to 219146 days ; which in 

 those remote ages was scarcely more than their true value, according to the 

 Egyptian mode of observation ; and if we equate this value to 7421 lunations ; 

 we obtain for the length of each lunation 29,53052 days. The true length of a 

 lunation was in the 18th century before Christ about 29,53060 days ; the error 

 being only one 12500th part of a day in each lunation, or, more accurately, 

 5916 ten thousandth parts of a day in 600 years. There can be no doubt that 

 the lunisolar cycle of 600 years was observed in the most remote antiquity.* 

 The knowledge of it, acquired in antediluvian times, would be preserved by the 

 survivors of the deluge ; and would be carried at the subsequent dispersion to 

 all countries. The Egyptians would thus have been led to pay particular atten- 

 tion to this period of 600 years ; and, when they noticed the remarkable fact, 

 that in the half of that period there occurred just 73 years with 366 days ; and, 

 consequently, that it would be equal to 300^ years of 365 days ; they would be 

 the more easily persuaded to adopt a wandering year, which connected itself so 

 readily with the cycle that was already in use among them. I here speak of the 

 men of learning among them ; for, as to the bulk of the population, all their 

 feelings would be in favour of a year of uniform length, and in opposition to the 

 nuisance of the 366th day, which, occurring so irregularly as it did, was a con- 

 stant source of vexation to them. The period of 300 years was thus the half of 

 the lunisolar cycle of 600 years, and at the same time the fifth part of the cycle 

 of 1500 years, which commenced at the time that the year began to wander, and 

 would terminate when the 1st of Thoth returned to its original place in respect to 

 the seasons ; when the sun would again attain to 12^" south declination at its noon. 

 Properly speaking, the period of 300 years was not cyclical. At the end of it, 

 nothing returned to the situation in which it was at the beginning of it ; but it 

 was the greatest common measure of the two cycles which the Egyptians used, 

 and consisted of an integral number of days ; it thus possessed two characters, 

 which entitled it to especial notice. Another period, also claiming especial 

 notice, was the great period of 3000 years, which was the least common multiple 



* It has been often remarked, that Josephus speaks of the cycle of 600 years as having been 

 known to the antediluvians ; accounting for their discovery of it by the great lengths of their lives. 

 —See Ant. Jud. I. 3. 9. 



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