vbi.. xLvrri.^ philosophical transactions. 443 



sible error, take Athens, whose latitude is made, by the best modem geogra- 

 phers, 38° 5' north. Hence is computed the oblique ascension 148° 12'. 



In the year before Christ 880, the time of the winter solstice was December 

 29, at 15 minutes past 6 o'clock in the morning, according to the vulgar reck- 

 oning; or, in the astronomical account, 28'' 18*^ 15"; and 60 days after this 

 brings us to Feb. 27, when the sun's place was IV 0° 6' 23"; his declination 

 south 11° 27' 18*; his right ascension 332° 11' 56"; whence we have his ascen- 

 sional difference := 9° 8' 1 5". Hence is computed the time of Arcturus's rising, 

 viz. 5'' 42™ 47'. By this it appears, that at Athens, in the year before Christ 

 880, and 60 days after the winter tropic, the star Arcturus rose at 19™ 20' after 

 sun-setting. 



But if we would inquire the time when it rose achronically, in the proper 

 sense of the word, we shall find it to be that year March the 3d. But though 

 this is what is properly meant by achronical rising; yet as a star at that time is 

 invisible, and consequently can be no rule for husbandmen, for whose use these 

 observations were intended; there is another achronical rising, called the appa- 

 rent one : this is when a star first appears above the eastern horizon after sun- 

 set; which therefore requires some certain depression of the sun in the opposite 

 part of the heavens, more or less according to the magnitude of the star required, 

 to become visible. 



It was said before, that in the year before Christ 880, Feb. 27, Arcturus rose 

 at Athens 19" 20^ after sun-set; but whether this, though a bright star of the 

 first magnitude, could be seen there so soon in the eastern horizon as even at 

 30 min. past sun-set, may well be questioned : and therefore Feb. 27, or the 6oth 

 day after the winter solstice, could not be there esteemed the day of the apparent 

 achronical rising of Arcturus. 



I have hitherto, says Mr. C, called it the star Arcturus , but it is not im- 

 probable that Hesiod meant the whole constellation Bootes. He calls it indeed 

 AITHP, and that word, according to Macrobius, signifies only a single star. 

 But whatever it might do in his time, it seems evident, that among the ancients, 

 and especially the poets, that distinction was not always nicely observed. If this 

 therefore should be the case with respect to Hesiod, the time of this rising of 

 Arcturus will be something more indeterminate, as a constellation cannot rise all 

 at once, nor is it now known how many stars this constellation in particular was, 

 in those early times, supposed to consist of. 



But further ; it has been hitherto taken for granted, that Hesiod is to be un- 

 derstood as speaking of Ascra, or some place in the neighbourhood of it ; but 

 this also is uncertain : for it was no unusual thing with the ancients to set down 

 in calendars, of this sort, observations on the risings and settings of the stars 

 made in very distant times and countries ; the latitudes of places being unattendetl 



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