851 



ft. THE SOLAR REGION. 



PLACETS AND THEIR SATELLITES. COMETS. BT *G OF THB 



ZODIACAL LIGHT. SWABMS OF METEOB-ASTEROIDS. 



ON passing, in the Uranological portion of the physical 

 description of the universe, from the heaven of the fixed stars 

 to our solar and planetary system, we descend from the 

 great and universal to the relatively small and special. 

 The domain of the Sun is the domain of one individual 

 fixed star amongst the millions revealed to us in the firma- 

 ment by telescopic aid the limited space in which veiy 

 various cosmical bodies, in obedience to the direct attraction 

 of a central body, revolve around it in more or less extended 

 orbits, whether they are isolated or encircled by other bodies 

 similar to themselves. Among the stellar bodies whose arrange- 

 ment we have endeavoured to consider in the sidereal portion 

 of the Uranology, there is, indeed, a class of those millions of 

 telescopic fixed stars double stars which exhibit special, 

 binary, or multiple systems ; but notwithstanding the analogy 

 presented by the forces by which they are impelled, they yet 

 differ -m their natural character from our solar system. In 

 them, se' f-luminous fixed stars revolve round one common 

 centre of gravity, which is not filled with visible matter; 

 while in our solar system dark cosmical bodies rotate around 

 a self-luminous body ; or, to speak more def nitely, around 

 one common centre of gravity, which lies at lifferent times 

 ither within or without the central body. "The 



