ASTRONOMY. gp 



faint luminous light. This light has not been 

 resolved into small stars, and Dr HERSCHEL be- 

 lieves it to be the effect of a luminous fluid, 

 Phil Trans. 1791. 



39. As the apparent motion of a body, in 

 any direction, may arise either from the real 

 motion of the body in that direction, or from 

 the motion of the spectator in the opposite j 

 so the apparence of the diurnal motion of the 

 heavenly bodies, round the earth, may either be 

 produced by the real revolution of the heavens 

 from east to west, or by the rotation of the 

 earth, on its axis, from west to east. 



This principle is conformable to the experience of 

 every day, and as there are, therefore, two ways of 

 accounting for the phenomena of the diurnal mo- 

 tion, we must choose that which is least liable to 

 objection from other quarters. 



40. It is no objection to the supposition, that 

 the diurnal motion of the heavens arises from 

 the motion of the spectator, that he himself is 

 not sensible of his motion. The motion which 

 any body has in common with other bodies, does 

 not affect its state with respect of those bodies, 

 and all the relative motions take place just as if 

 the motion common to them all had no existence. 



This 



