108 WEIGHT OF THE ATMOSPHERE. 



wide through the dense forest as thoroughly as if a 

 thousand* woodmen had been at work there for 

 many years. 



When whirlwinds pass from the land to the sea 

 they create waterspouts ; of which we shall have 

 something to say in another chapter. Meanwhile, 

 we think it may be interesting to give the following 

 miscellaneous information regarding the atmosphere, 

 gathered from the work of Dr. Buist, who devoted 

 much earnest study to the subject of atmospheric 

 phenomena. 



" The weight of the atmosphere is equal to that 

 of a solid globe of lead sixty miles in diameter. Its 

 principal elements are oxygen and nitrogen gases, 

 with a vast quantity of water suspended in them in the 

 shape of vapour ; and, commingled with these, a 

 quantity of carbon in the shape of fixed air, suffi^ 

 cient to restore from its mass many-fold the coal 

 that now exists in the world Water is not com- 

 pressible or elastic ; it may be solidified into ice or 

 vaporized into steam: but the air is elastic and com- 

 pressible. It may be condensed to any extent by 

 pressure, or expanded to an infinite degree of tenuity 

 by pressure being removed from it. It is not liable 

 to undergo any changes in constitution beyond these, 

 by any of the ordinary influences by which it is 

 affected." 



If the heating and cooling process which we 

 have described as being carried on between the 

 equator and the poles were to cease, we should 



