THE TURNING OF THE EARTH 105 



setting the sun at the centre, the earth in an orbit about it, 

 and the " circle of the animals " still outside of that. Let us 

 do the same. 



It is easy enough to see that if the earth is on one side of 

 the sun, as at E, and its daily revolution makes the sun appear 

 to " rise," the sun will be seen to come up in the direction of 

 the group of stars which lie against the face of the sky opposite, 

 say the constellation of Leo. When the earth has swept round 

 a quarter of a turn, at E 1 , then the sun will seem to rise in Aries, 

 and so on around the whole circle. All this is simple enough 

 and satisfactory too, in a way ; but there are many points to 

 tax credulity. For example, one must suppose that, as the 



corn, 



FIG. 10. 



earth's axis is always pointed in the direction of the pole-star, 

 it sweeps round the sun always tilted on its side, and always at 

 the same tilt. But this would explain the change of the length 

 of days. If the earth on one side of the sun leaned a little 

 so that one pole would be in darkness all the time, then if it 

 kept leaning the same way, when it got around to the opposite 

 side of the circle, this dark pole would be constantly in the 

 sunlight. And this is exactly what happens. So the seeming 

 difficulty becomes an added proof. 



But what a tipsy and disconcerting vision it summons ! 

 this giant earth, careening about the sun in a plane, but 

 always turned partly on its side, as a ship buoy often floats 

 upon the surface of the water. Yet, how much it explains ; 

 how it simplifies ! What must have been the glow of pleasure 

 to him who first reasoned it out ! 



