Ct.lMATK. 14? 







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CHAPTER IV, 



Climate. 







"The body, moulded by the clime, endures 

 Equator heat, or hypoborean frost, 

 Except by habits foreign to its turn, 

 Unwise you counteract its forming pow'r." 



Armstrong. 



IN the present chapter we shall very briefly consider the prom- 

 inent causes which affect the climate of the various portions of 

 the earth's surface. The subject is a very important one and we 

 can do little else than give the great outlines, and must therefore 

 refer the reader to the more elaborate works of Leslie, Daniell, 

 and Kaemtz. 



The primary cause of all heat upon the surface of the earth, 

 and its superincumbent atmosphere, is the sun, whose rays may 

 also be regarded as the source of all life upon our planet. In the 

 preceding pages, we have, somewhat at length, illustrated the man- 

 ner in which the sun apparently changes its position in the heavens, 

 traversing during the year through the twelve signs of the Zodi- 

 ac, in the path called the ecliptic, which is inclined at an angle of 

 23 28' to the celestial equator, which it crosses in two opposite 

 points called the equinoctial points. 



The celestial equator, we have shown to be in the same plane 

 as the equator upon the earth, consequently, as the earth turns on 

 its axis, it will happen that the rays of the sun, whenever it may be 

 situated in the celestial equator, L c. at the time of the equinoxes, 

 will fall vertically, or perpendicularly upon all those places situated 

 upon or near to the terrestrial equator. Twice a year, viz : on 

 the 21st of March and the 21st of September, the sun is in those 

 points of the ecliptic which cross the equator, and at this time 

 its rays aro vertical at noon at the equator, as we have just de- 



