SKCT. XXXVH. FIXED STARS. 361 



The ratio of the forces which fixed the nature of the 

 celestial orbits is thus easily explained ; but the circum- 

 stances which determined these ratios, which caused 

 some bodies to move nearly in circles and others to 

 wander toward the limits of the solar attraction, and 

 which made all the heavenly bodies to rotate and re- 

 volve in the same direction, must have had their origin 

 in the primeval state of things ; but as it pleases the 

 Supreme Intelligence to employ gravitation alone in the 

 maintenance of this fair system, it may be presumed to 

 have presided at its creation. 



SECTION XXXVII. 



The Fixed Stars Their Numbers Estimation of their Distances and 

 Magnitudes from their Light Stars that have vanished New Stars- 

 Double Stars Binary and Multiple Systems Their Orbits and Periods 

 Orbitual and Parallactic Motions Colors Proper Motions General 

 Motions of all the Stars Clusters Nebulae Their Number and Forms 

 Double and Stellar Nebulae Nebulous Stars Planetary Nebulae 

 Constitution of the Nebula?, and Forces which maintain them Distribu- 

 tion Meteorites Shooting Stars. 



GREAT as the number of comets appears to be, it is 

 absolutely nothing when compared with the multitude of 

 the fixed stars. About 2000 only are visible to the 

 naked eye ; but when we view the heavens with a 

 telescope, their number seems to be limited only by the 

 imperfection of the instrument. In one hour Sir Wil- 

 liam Herschel estimated that 50,000 stars passed through 

 the field of his telescope, in a zone of the heavens 2 in 

 breadth. This, however, was stated as an instance of 

 extraordinary crowding ; but, on an average, the whole 

 expanse of the heavens must exhibit about a hundred 

 millions of fixed stars within the reach of telescopic 

 vision. 



The stars are classed according to their apparent 

 brightness, and the places of the most remarkable of 

 those visible to the naked eye are ascertained with 

 great precision, and formed into a catalogue, not only 

 for the determination of geographical positions by their 

 occultations, but to serve as points of reference for 

 marking the places of comets and other celestial phe- 

 HH 



