32 MARS. [Lesson vn. 



tion to the light arid heat at the earth, nearly as 

 43 to 100. His diameter or axis is nearly 4200 

 miles, from hence it may be shewn that his bulk 

 is 7-24ths of the Earth's. Dr. Hooke, in the year 

 1665, observed several spots in Mars : observations 

 on these spots and their motion, by the noted 

 astronomers Cassini and Herschel, have at length 

 determined the rotation of this planet on his axis 

 to be performed in 24 hours f very nearly, which 

 is the length of his day. 



Mars, when observed through a telescope is seen 

 to increase and decrease like the Moon, with this 

 exception that he is never cornicular, or horned : 

 from this we may infer that he shines not by his 

 own light, and that his orbit includes that of the 

 Earth. 



This planet when viewed by the unassisted eye, 

 appears smaller than Venus, and redder ; having 

 a ruddy troubled colour : whether this arises from 

 the planet being of such a nature as to reflect the 

 red rays of light best, or from a thick atmosphere 

 attending it, is rather uncertain. But be this as 

 it will, it appears pretty manifest that his sanguine 

 complexion has obtained him a post of eminence 

 among the pagan deities. 



Virgil, and some other of the ancient poets, give 

 us lively descriptions of him : they represent him 

 as riding in a high chariot drawn by two horses, 

 Fear and Terror; and, that the god may sit at 

 his ease, his sister Bellona is employed in hold- 

 ing the reins and driving. However, though 

 earthly poets have honoured him with these at- 

 tendants, 



