35° 



PHYSIOGRAPHY. 



[chap. 



orbit is, it is insignificant when compared with the enormous 

 distances of the so-called fixed stars. If, therefore, the 

 north pole of the earth points towards the pole-star at one 

 part of the earth's orbit, it continues to point towards it all 

 through its journey, though that journey forms an enormous 

 circuit in the heavens.^ 



Reference to Fig. 112 will now show plainly enough how 

 the incHnation of the earth's axis affects the amount of 



VERNAL. 

 EQUINOX 



® 



SUMMER 

 SOLSTICE 



WINTER 

 SOLSTICE 



AUTUMNAL 

 EQUINOX 



Fig. 112. — Diagram showing the earth's relation to the sun at different seasons. 



light and heat which the globe receives from the sun at 

 different seasons. Suppose that the earth is in the position 



a slow change of position, so that it does not always point to exactly the 

 same spot in the heavens. But this movement is so slow that it would 

 take 25,868 years for the pole to make a complete revolution. 



* If one walks in a circle ten yards in diameter, the apparent direc- 

 tion of objects fifty yards off will be obviously altered at every step ; 

 while the change of bearing of the spire of a distant church can only 

 be detected by a theodolite ; and that of a remote mountain top will 

 appear to remain unchanged, even with such help. 



