THE PLANETS. 421 



The sixth satellite of Uranus: William Herschel, February 28, 



1794. 

 The third satellite of Uranus: William Herschel, March 26, 



1794. 



C. The Nineteenth Century. 



CERES*: Piazzi, at Palermo, January 1, 1801. 



PALLAS*: Olbers, at Bremen, March 28, 1802. 



JUNO*: Harding, at Lilienthal, September 1, 1804. 



VESTA*: Olbers, at Bremen, March 29, 1807. 



(During 38 years no planetary discoveries were made). 



ASTREA*: Hencke, at Driesen, December 8, 1845. 



NEPTUNE: Galle, at Berlin, September 23, 1846. 



The first satellite of Neptune: W. Lassell, at Starfield, near 

 Liverpool, November, 1846; Bond, at Cambridge (U. S.). 



HEBE*: Hencke, at Driesen, July 1, 1847. 



IRIS*: Hind, in London, August 13, 1847. 



FLORA*: Hind, in London, October 18, 1847. 



METIS*: Graham, at Markree- Castle, April 25, 1848. 



The seventh satellite of Saturn (Hyperion): Bond, at Cam- 

 bridge (U. S.), September 16-19; Lassell, at Liverpool, 

 September 19-20, 1848. 



HYGEIA*: De Gasparis, at Naples, April 12, 1849. 



PARTHENOPE*: De Gasparis, at Naples, May 11, 1850. 



The second satellite of Neptune : Lassell, at Liverpool, August 

 14, 1850. 



VICTORIA*: Hind, in London, September 13, 1850. 



EGERIA*: De Gasparis, at Naples, November 2, 1850. 



IRENE*: Hind, in London, May 19, 1851; and De Gasparis, 

 at Naples, May 23, 1851. 



In this chronological summary, 18 the principal planets are 



15 In the history of the discoveries, it is necessary to dis- 

 tinguish between the epoch at which the discovery was made, 



K 2 



