FIG. 187. SIR JOHN HERSCHEL. 

 CHAPTER XVI. 



ASTRONOMY OF THE NINETEENTH CENTURY. 



THE discovery by Galileo of the satellites of Jupiter added to the 

 number of the planetary bodies which had been known from time 

 immemorial, and besides which the existence of no others had been 

 suspected. True, the "Medicean stars" were only secondary bodies, 

 but their discovery dissipated for ever the idea that the heavenly bodies 

 must be seven in number, namely, the sun, the moon, Mercury, Venus, 

 Mars, Jupiter, and Saturn. No doubt much patient watching of the 

 heavens must have been practised before even these anciently-known 

 planets were distinguished. But it would seem that the planet which 

 Sir W. Herschel added to our system in 1781 (page 260) had escaped 

 observation, although it is just visible under favourable conditions. It 

 is not without probability that the explanation of the eighth planet of 

 the old Burmese astronomers is ascribed to the planet Uranus. A 



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