VOL. XXXV.] PHILOSOPHICAL TRANSACTIONS. IQS 



fore was reckoned the place of the star at that time by Hipparchiis. Add 1° 

 40', for 265 years between Hipparchus and Ptolemy, and we shall have its 

 place, in Ptolemy's account, Aries 0° 33', with 5° 24' north latitude. But the 

 22d star of Pisces, in Ptolemy's catalogue, has the same longitude and latitude, 

 with sufficient exactness, viz. Aries 0° 40', with north latitude 5° 20', and is 

 Media trium in Lino Boreo Piscium (>i Bayero.) Hence it cannot be doubted 

 but that this star, which P. Souciet takes to have been once a star of the first 

 magnitude, was no other than the said 22d of Pisces, which in the British 

 catalogue, fitted to the year 169O, is set down in Aries 22° 294-', with north 

 latitude 5° 2l'. 



How Hipparchus came to reckon this star to be in the fore-foot of Aries, 

 does not at present appear ; but it is not unlikely that these commentaries of 

 his upon Aratus, were written some time before he set about making his cata- 

 logue of the fixed stars ; when he might change his opinion, and replace it in 

 the line of the fishes, to which it seems more properly to belong. 



Be that as it may, we will for once, suppose with P. Souciet, this star to have 

 been in the beginning of the zodiac, or of the constellation of Aries, and that 

 at the time of the first fixing the colures, that of the vernal equinox passed 15° 

 in consequence of it. Now anno ineunte 169O, this star being in Aries 22° 

 294-', if we add 15°, we shall have Taurus 7° 294-' for the point in the ecliptic 

 that was then the beginning of the zodiac. Now 374-°, ^t 50" per annum, 

 gives 2700 years ; from which deducting 169O, we shall have 1010 years before 

 Christ. But this star having 5° 2]' north latitude, the colure, when it passed 

 over it, intersected the ecliptic in 2° 20' less longitude ; which gives the time 

 168 years later, or but 842 years before Christ. So that malgre cette grande 

 decouverte, the new system of chronology is so far from being refuted, that 

 it seems to be hence very much confirmed, at least in the opinion of the 

 reverent Pere. 



I have assumed the latitude to which Hipparchus might have adapted his cal- 

 culations, to be 36°; because I find in page 14 of the aforesaid edition, that he 

 makes the longest tropical day 14^ 30"'. And in page 29, he tells us, that the 

 southern star in the left foot of Bootes (u Bayero) having 27° 20' north declina- 

 tion, was above the horizon, M*" 57"^; whence it follows, that the latitude 

 must be 36° 5'. He also tells us, in the same page 29, that this star set when 

 22° of Capricorn culminated, and 6° of Taurus ascended ; repeating the same 

 thing in page 39, which leaves no room to suspect that those numbers are not 

 the same that Hipparchus had computed. I therefore thought it worth while 

 to inquire in what latitude 6° of Taurus rises when 22° of Capricorn is on the 

 meridian ; and with the obliquity of the ecliptic, as now we have it, the latitude 



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