/iMracles. 



very thin state to a height of eighty or ninety 

 miles; at least, at that height we should find 

 a more perfect vacuum than can be produced 

 by artificial means. The weight of all the air 

 on the globe would be 11 2-3 trillion pounds if 

 no deduction had to be made for space filled by 

 mountains and land above sea-level. As it is, 

 the whole bulk weighs something less than the 

 above figures. 



As we have said, the air envelopes the globe 

 to a height at sea-level of eighty or ninety 

 miles, gradually thinning out into the ether 

 that fills all interstellar space. We live and 

 move on the bottom of a great ocean of air. 

 The birds fly in it just as the fish swim in the 

 ocean of water. Both are transparent and 

 both have weight. Water in the condensed 

 state is heavier than the air and will seek the 

 lowest places, but when vaporized, as in the 

 process of evaporation, it is lighter than air 

 and floats upward. In the vapor state it is 

 transparent like steam. If you study a steam 

 jet you will notice that for a short distance 

 after it issues from the boiler it is transparent, 

 but soon it condenses into cloud. 



If we could see inside of a boiler in which 

 steam had been generated, all the space not 

 occupied with water would seem to be vacant, 

 since steam before it is condensed is as trans- 

 parent as the air. We will, however, speak of 

 this subject more fully under the head of 



