42 GEORGIUM SIDUS. [Lesson X- 



vered. This new-found planet was discovered on 

 the 13th of March, 1801, and is known by two 

 titles : the one of Gcorg'mm Sidus, was bestowed 

 upon it by the discoverer, in honour of our present 

 Sovereign. The other of Herschel was long given 

 it by the chief astronomers of all nations, as a 

 proper testimony of respect to the assiduity and 

 abilities of the person who discovered it. The 

 name by which it is now designated by continen- 

 tal astronomers, is Uranus. 



Georgium Sidus, or Herschel, is characterized 

 by the mark $ , being the initial of the discoverer's 

 name, with a cross bar, intersecting the horizontal 

 bar of the H, to represent a cross, and thereby to 

 denote that the discovery of this planet was after 

 the birth of Christ. Herschel's mean distance 

 from the sun is about nineteen times that of the 

 earth, viz. about 1800 millions of miles ; he per- 

 forms a revolution through his orbit in 30,68"9 

 days very nearly, being almost ninety of our 

 years ; the light and heat he derives from the sun 

 are about the 362d part of those at the earth, cal- 

 culating on the hypothesis before explained. This 

 planet appears of a bluish white colour, and its 

 brilliancy is between that of Venus and the 

 Moon. With a telescope that magnifies about 

 300 times, he appears to have a very well defined 

 visible disc. In a very fine clear night, when the 

 moon is absent, he may be perceived by a good 

 eye without a telescope. 



The time of this planet's diurnal rotation is not 

 yet discovered : his axis is found to be 35,865 



English 



