80 The Earth considered as a Planet, 



pic of Cancer, and is vertical to those 

 who live under that circle. About the 

 23d of September the earth is in Aries, 

 and the sun in Libra, and the central so- 

 lar ray again terminates at the equator ; 

 consequently the sun again appears in the 

 celestial equator, and is vertical to those 

 who live under it. 



We have seen, that, as the sun appears 

 to move in the ecliptic, from the vernal 

 equinox to the tropic of Cancer, it gets 

 to the north of ths equator, or its decli- 

 ivition towards our pole increases. There- 

 fore, from the vernal equinox, when the 

 days and nights are equal, till the sun 

 comes to the tropic of Cancer, our days 

 lengthen, and our nights shorten ; but, 

 when the sun comes to the tropic of Can- 

 cer, it is then in its utmost northern lim- 

 it, and returns in the ecliptic to the equa- 

 tor again. During this return of the sun, 

 its declination tov/urds our pole decrea^s, 

 and consequently the days decrease, and 

 rights increase, till the sun is ar- 

 rived in die equator 'again, and is in the 

 autumnal equinoctial point, when the 

 (I ivs ts will ngain be equal. As the 



sun moves from thence towards the tro- 



