100 . COSMOS. 



Sequence of the Planetary Discoveries (of principal and 

 secondary planets) since the Invention of the Telescope 

 in the Year 1608. 



(A.) The Seventeenth Century. 



Four satellites of Jupiter : Simon Marius, at Ansbach, De- 

 cember 29, 1609 ; Galileo, January 7, 1610, at Padua. 



Triple configuration of Saturn : Galileo, November, 1610 ; 

 Hevelius, hypothesis of two lateral bars, 1656 ; Huygens', 

 final discovery of the true form of the ring, December 7, 

 1657. 



The sixth satellite of Saturn (Titan) : Huygens, March 25, 

 1655. 



The eighth satellite of Saturn (the outermost, Japetus) : Do- 

 min. Cassini, October, 1671. 



The fifth satellite of Saturn (Rhea) : Cassini, December 23, 

 1672. 



The third and fourth satellites of Saturn (Tethys and Dione) : 

 Cassini, end of March, 1684. 



(B.) The Eighteenth Century. 



Uranus : "William Herschel, May 13, 1781, at Bath. 



The second and fourth satellites of Uranus : William Her- 

 schel, January 11, 1787. 



The first satellite of Saturn (Mimas) : William Herschel, 

 August 28, 1789. 



The second satellite of Saturn (Enceladus) : William Her- 

 schel, September 17, 1789. 



The first satellite of Uranus : William Herschel, January 18, 

 1790. 



The fifth satellite of Uranus : William Herschel, February 

 9, 1790. 



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 Dresden, December 8, 1845. 



