Chap. 18.] ACCOTJNT OF THE WOELD. 51 



is equal to the day, in the Spring and in the Autumn, 

 when he is opposed to the centre of the earth \ in the 8th 

 degree of Aries and Libra^. The length of the day and the 

 niglit is then twice changed, when the day increases in length, 

 from the winter solstice in the 8th degree of Capricorn, and 

 afterwards, when tlie night increases in length from the 

 summer solstice in the 8th degree of Cancer^. The cause of 

 this inequality is the obliquity of the zodiac, since there is, 

 at every moment of time, an equal portion of the firmament 

 above and below the horizon. But the signs which mount 

 directly upwards, when they rise, retain the light for a longer 

 space, while those that are more oblique pass along more 

 quickly. 



CHAP. 18. (20.) — WHY THTJJiTDEE IS ASCEIBED TO JXJPITEE. 



It is not generally known, what has been discovered by 

 men who are the most eminent for their learning, in con- 

 sequence of their assiduous observations of the heavens, that 

 the fires which fall upon the earth, and receive the name of 

 thunder-bolts, proceed from the three superior stars'*, but 

 principally from the one which is situated in the middle. It 

 may perhaps depend on the superabundance of moisture from 

 the superior orbit communicating with the heat from the 

 inferior, which are expelled in this manner^ ; and hence it 

 is commonly said, the thunder-bolts are darted by Jupiter. 

 And as, in burning wood, the burnt part is cast off" with a 

 crackling noise, so does the star throw ofi" this celestial fire, 

 bearing the omens of future events, even the part which is 



^ " centrum ten'se ; " the equator, the part equally distant from the 

 two poles or extremities. 



^ It may be remarked, that the equinoxes did not actually take place 

 at this period in the pomts mentioned by Phny, but in the 28th deojrees 

 of Pisces and Yirgo respectively ; he appears to have conformed to the 

 popular opinion, as we may learn from Columella, Hb. ix. cap. 14. The 

 degrees mentioned above were those fixed by the Greek astronomers who 

 formed the celestial sphere, and wliicli Avas about 138 years before the 

 Christian ara. See the remarks of Marcus in Ajasson, ii. 246 & 373, 374. 



3 The same remark apphes to this as to the former observation. 



* " siderum." 



° The hypothesis of the author is, that the excess of moisture in the 

 orbit of Saturn, and the excess of heat in that of Mars, unite in the orbit 

 of Jupiter and are discharged in the form of thunder. 



e2 



