ASTRONOMY. 31 



42. The physical and mechanical objections 

 to the rotation of the earth being entirely ob- 

 viated, while many press so hard upon the op- 

 posite hypothesis, the simplicity of the ex- 

 planations afforded by the former, justifies us 

 in admitting it as the cause of the apparent 

 diurnal revolution of the heavens, at least till 

 some fact, or some principle inconsistent with it 

 shall be discovered. 



SECT. II. 



OF THE ATMOSPHERICAL REFRACTION. 



43. A RAY of light, in passing through the at- 

 mosphere, is bent into a curve, in the same ver- 

 tical plane with the original ray, and concave 

 toward the surface of the earth. But the ob- 

 ject from which the ray comes, is seen in the 

 direction which the ray has when it enters the 

 eye, and therefore it appears elevated above its 

 true place. This is called the Atmospherical, 

 and sometimes the Astronomical Refraction. 



a. The effect of the atmospheric refraction alters the 

 place of an object only in a vertical plane ; it in- 

 creases 



