18 



THE WORLD. 



west, being at his left hand, whilst A would assert it to be east, 



C 



being at his right hand. The terms therefore, north, south, east 

 and west, are only relative expressions, and not absolute direc- 

 tions. It will be necessary to remember this, and we may also 

 remark, the same is true of the expressions up, and down. What 

 would be up to an observer at A, would be in the direction N A, 

 but this would be down to an observer at B. Hence we must 

 learn to consider up, as away from the earth, and down as the 

 direction to its centre, and therefore not absolute directions in 

 space but only relative terms. Now as the sun and the stars are 

 observed after certain regular intervals to appear in the east, 

 apparently move over the heavens, and set in the west, the natural 

 inference is, that they are revolving in vast circles around th^ 

 earth, which itself is the immovable centre. Below we have given 



an engraving which represents the earth as the centre, and the 



