THE SIDEREAL UNIVERSE. 741 



tion of all created things, Avliich its rays alone protect 

 from the horrible mantle of ice perpetually threatening 

 to invade them. 



Compared to our globe and to the other orbs which it 

 enchains in their orbit round itself, the sun is of enormous 

 dimensions. It is about a million and a half times the 

 bulk of the earth, and has been calculated to contain seven 

 hundred times the mass of all the planets together which 

 circulate in its system. 



Astronomers have not rested content with knowing the 

 volume of the sun; they have attempted to estimate its 

 weight, and have succeeded. By comparing its weight 

 with that of the earth, they have made out that it would 

 require a large number of the latter to counterbalance it. 

 If we supposed the existence of a prodigious balance, 

 which allowed us to place the sun in one scale, Ave should 

 have to put 350,000 terrestrial globes into the other in 

 order to Aveigh it properly. 



The orbit of the earth is rigidly hmited to 91,000,000 

 miles from the sun. Some planets roll at a much 

 greater distance from this luminary; others much nearer. 

 He scorches the one, and condemns the other to the em- 

 pire of eternal frost. ]\Iercury, his nearest neighbour, al- 

 most in a state of combustion, is only 37,000,000 miles off. 

 Neptune, Avhich is doubtless all covered with ice, rolls 

 in the furthest orbit of the system at 2,854,000,000 miles 

 from the blazing star, and thus it only accomplishes its 

 revolution in 104 years, which constitute its year! 



However dazzling may be the splendour of tlie sun, it 

 was discovered 250 years ago to display here and there 

 some black patches, very small, it is true, in compari- 

 son with the extent of its surface, but in reality of 

 vast extent relatively to the dimensions of our globe. 



