THE OUTER PLANETS. 113 



Fifty years elapsed before another satellite of 

 Saturn was discovered. In 1888 W. H. Picker- 

 ing commenced a photographic search for new 

 satellites of the planet. At last, on developing 

 some photographs of Saturn, taken on August 16, 

 17, and 18, 1898, he found traces of a new 

 satellite which he named " Phoebe." But, as the 

 satellite was not seen or photographed again for 

 some years, many astronomers were sceptical as 

 to its existence. However, photographs taken 

 in 1900, 1901, and 1902 revealed the satellite, 

 which was again photographed in 1904, and seen 

 visually by Barnard in the same year with the 

 40-inch Yerkes telescope. At that time the dis- 

 coverer brought out the amazing fact that the 

 motion of the satellite is retrograde a fact which 

 he attempts to explain by a new theory of the 

 former rotation of Saturn. He likewise demon- 

 strated that its distance from Saturn varied 

 from 6,120,000 to 9,740,000 miles. Early in 1905 

 Pickering announced the discovery of a tenth 

 satellite of Saturn, which received the name of 

 Themis, with a period and mean distance nearly 

 similar to Hyperion, so that Sir John Herschers 

 idea of Hyperion being an asteroidal satellite is 

 being confirmed after a lapse of half a century. 



If little is known of the globe of Saturn, still 

 less is known regarding Uranus. Dusky bands 



