BOOK OF NATURE LAID OPEN. 201 



ly occasioned by the obliquity of the sun's rays, as 

 they, at those seasons, fall on our atmosphere) would 

 be rendered still more intolerable and severe. 



The magnitude of the Moon is said to be about 

 one-fiftieth of that of the Earth, about which she 

 moves at the distance of 236.847 miles, and com- 

 pletes her revolution in somewhat less than twenty- 

 eight days, travelling at the rate of 2,270 miles an 

 hour. 



Mars, whose diameter is little more than one half 

 of our Earth, moves next her in the order of the pla- 

 nets: he completes his revolution in something less 

 than 687 of our days ; so that his year is nigh twice 

 the length of ours, while his light and heat are con- 

 sidered to be not quite the half of what we enjoy; 

 Mars revolves at the rate of 55,223 miles an hour, 

 and appears in the heavens of a dusky red colour. 



What are called the !New Planets are to be found 

 between the orbits of Mars and of Jupiter; but as 

 so little is yet known respecting them, we shall just 

 mention their names, with the dates of their disco- 

 veries: Ceres was discovered by M. Piazzi in Si- 

 cily, on the 1st Jan 1801; Pallas was discovered 

 by Dr Olbers, of Bremen, on the 28th of March, 

 1802; Juno was discovered by Mr. Harding, of 

 Lilienthal, Bremen, 1st Sept. 1804; and Vesta was 

 discovered by Dr. Olbers, 29th March, 1807. These 

 being so very small, in comparison with the others, 

 Dr. Herschel does not deign to denominate them 

 planets, but Asteroids. 



