76 PNEUMATICS. 



In England it is found that Keswick and Kendall, 

 situated among the mountains, have 67 and 69 inches 

 of rain annually, while places in the level country and 

 on the sea-coast have only 24 inches. But although 

 more rain falls in mountainous than in level coun- 

 tries, the depth is greater at the bottom than at the 

 top of a mountain, and close to the surface of the 

 ground than at a distance from it. 



Garneriris Balloon, 



The hydrogen gas of Garnerin's balloon weighed 

 44 pounds, which being 1 3 times lighter than atmos- 

 pheric air, would of course float - 572 pounds. 

 Suppose the balloon alto- ? n d 



gether to weigh - j 

 Add for the passengers, &c. 400 512 



Weight remaining to work upon 60 pounds. 



. 



Coal Gas Balloons. 



Mr. Green has the merit of being the first person 

 who tried experiments on the buoyant properties of 

 coal gas. In some of his preliminary trials he ascer- 

 tained that the ascensive force of a small balloon, 

 three feet in diameter, was equal to eleven ounces ; 

 and when filled in the old way, with hydrogen gas, 

 not more than fifteen ounces. 



Greatest Elevation attained. 



Gay Lussac, in a balloon, reached the height of 

 23,040 feet, or 4 miles 1920 feet. 



Colour of the Sky. 



Although the sky is known to have a blue colour, 

 the air itself is altogether colourless and invisible. 

 The blue colour is occasioned by the vapours in the 



