System of the Universe. 257 



call fixed stars. The others are opake bodies, 

 as the Earth which we inhabit, not luminous 

 of themselves, but which shine by a borrowed 

 light ; in few words, luminous by reflecting that 

 light which comes from a luminous star: such 

 are the planets of the first and second order, and 

 the comets. 



The stars of the firmament are said to be fixed, 

 because they have been generally observed to pre- 

 serve the same distance from each other : they do 

 not all appear to us of the same magnitude, 

 whether they are really different in size one from 

 the other, or whether they appear so to us in 

 consequence of their different distances. It is 

 probable that both these causes operate to exhibit 

 the fixed stars of such various magnitudes. Be 

 this as it may, astronomers have agreed in distri- 

 buting the fixed stars into six different classes, 

 according to their relative magnitude, inde- 

 pendent of those small stars which compose the 

 white and brilliant spaces in the heavens, which 

 are denominated nebulae, and that bright band 

 which extends across our hemisphere, and which 

 from its lucid appearance is termed the milky way. 

 Those which are distinctly visible are fewer in 

 number than might be supposed. The British 

 catalogue, which, besides the stars visible to the 

 naked eye, includes a great number which can- 

 not be seen without the assistance of a telescope, 

 contains no more than three thousand in both he- 

 mispheres. The number of stars discoverable,, 



