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of them, unless it appears that Chiron knew how to give them their true place. It was easy for so great a master of astronomy as Sir Isaac Newton, to calculate where the Solstices ought to be placed in the year of our Lord 1689;' and to know how many years have passed since they were in the fifteenth degrees of the constellations. But though we should allow that Chiron supposed them, in his time, to be in this position; yet if he was really mistaken, no argument can be formed from Chiron's position of them. For supposing the true place of the Solstices in the days of Chiron, to be in the nineteenth degrees of the constellations; it will be evident from what was their true place in the year of our Lord 1689, as well as from what was their place Ann. Nabonass. three hundred and sixteen, that the time of Chiron's making his scheme of the heavens was about three hundred years earlier than our great and learned author supposes,

Chron. of the Greeks, p. 86.

though Chiron erroneously placed the Soltices at that time in the fifteenth degrees of the constellations, instead of the nineteenth; and whether Chiron might not mistake four or five degrees this way or that way, we may judge from what follows.

Chiron's skill in astronomy Was so imperfect, that we must suppose he could hot find the true place of the Solstices with any tolerable exactness. The Egyptians were the first who found out, that the year consisted of more than three hundred and sixty days. Strabo informs * us, that the Theban priests were the most eminent philosophers and astronomers; and that they numbered the days of the year, not by the course of the moon, but by that of the sun; and that to twelve months, consisting each of thirty days, they added five days every year. Herodotus testifies the same thing.' "The Egyptians," pays he, "were the first who found out the

* Strabo. Geogr. lib. 17. j). 816.
'Hcrodot. lib. 2. cap. 4.

length of the year." And he tells us particularly what they determined to be the true length of it, namely, "twelve months of thirty days each, and five days added besides." Diodorus Siculus says, "The Thcbans," i. e. the priests of Thebes in Egypt, "were the first who brought philosophy and astrology to an exactness;" and he adds, "They determined the year to consist of twelve months, each of thirty days; and added five days to twelve such months, as being the full measure of the sun's annual revolution.'^ Thus, until the Egyptians found out the mistake, all astronomers were in a very great error; supposing the sun's annual motion to be performed in three hundred and sixty days.

It may perhaps be here said, that the Egyptians had improved their astronomy before Chiron's days; and that Chiron may

f Diodor. Sic. Hist. lib. 1. p. 32. Diodorus indeed mentions the teragtov, or six hours, which were added afterwards; but these were not accounted to belong to the year so early as the five days.

be supposed to have been instructed by them, and- sp have been a pretty good astronomer: to this I answer:

If the Egyptians had improved their astronomy before Chiron's time; yet the Greeks were ignorant of this measure of the year, until Thales went to Egypt, and conversed with the priests of that nation. Thales, says Laertius,* was the first who corrected the Greek year. And this opinion of Laertius is confirmed by Herodotus, who represents Solon, a contemporary of Thales, in his conference w^th Croesus very remarkably mistaking the true measure of the year. Thai es had found out, that the year consisted of three hundred and sixty-five days; but the exact particulars of what he had learned in this point, were not immediately known all over Greece, and so Solon represents to Croesus, that the year consisted of three hundred and seventy-five days; for he represents it as necessary to add a whole month, i. e. thirty days, every other year, to adjust

'Lacrf. in Vita Thaletis.

PREFACE. X1U

the year then in use to its true measure,1 The notion therefore of the received computed year's being too short, was new in Solon's time. He was apprised that it was so; but what Thales brought from Egypt upon the subject was not yet generally known or understood; and thus Solon made mistakes in his guesses about it. Thales, according to the vulgar account, lived above six hundred years after Chiron, and above three hundred years after him, according to Sir Isaac Newton; therefore Chiron was entirely ignorant of all this improvement in astronomy. Chiron supposed three hundred and sixty days to be a year, and if he knew no better how to estimate the sun's annual motion, his <wt**r* Oxi/f**«, his draughts of the constellations must be very inaccurate; he could never place the Solstices with any tolerable exactness, but might easily err four or five degrees in his position of them; and if we had before us the best scheme which he could draw, I dare say, we could

- i

■j '.. .;: '•■!$ "Herodot. 1. 1. c. 32.

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