218 OUTLINES OF NATURAL PHILOSOPHY. 



which we see in the heavens. As it cannot be 

 doubted, that the fixed stars are luminous bodies 

 like the Sun, it is probable that they are not near- 

 er to one another than the Sun is to the nearest of 

 them. When, therefore, two stars appear like a 

 double star, or very near to one anbther, the one 

 must be placed far behind the other, but nearly in 

 the same straight line, when seen from the Earth. 

 The same must hold, at least in a certain de- 

 gree, wherever a great number of stars are seen 

 concentrated in a small spot. In the starry nebu- 

 lae, therefore, such as the Milky Way, which de- 

 rive their light from the number of small stars, ap- 

 pearing as if in contact with one another, it is 

 plain, that the most distant of these must be many 

 thousand times farther off than the nearest, and 

 light must, of course, require many thousand years 

 to come from them to the Earth. The poet, per- 

 haps, has been taxed with exaggeration, who 

 spoke of 



" Fields of radiance, whose unfading light 



" Has travelled the profound six thousand years, 



" Nor yet arrived in sight of mortal things." 



Yet the fields which he describes, are far within 

 the circle to which the observations of the astrono- 

 mer extend ! 



AP- 



