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phere is great, always springing back to its former 

 bulk when confined and liberated. It likewise expands 

 or contracts on being heated or cooled. The pressure 

 of this substance is enormous, but so evenly is it exert- 

 ed upon things that the great weight is scarcely notice- 

 able. The amount of pressure is about fifteen pounds 

 to every square inch of surface. The atmosphere ex- 

 tends upwards many miles, but the greatest bulk of it 

 lies below the summits of high mountains. The high- 

 er we ascend the more rare it becomes, and this causes 

 the difficulty in breathing experienced by those who 

 ascend to great heights for observation or amusement. 



Climate is the amount of heat or cold, moisture or 

 dryness which the atmosphere contains. Some climates 

 are uniform, as in the torrid zones, and others vary as 

 in the temperate regions. The country in some places 

 is much healthier than in others, owing to various 

 causes. 



The formation of rain, dew, hail and snow are inter- 

 esting and come in connection with the atmosphere. 

 From all bodies of water the sun is constantly drawing- 

 moisture which may be seen in the appearance of rays 

 or columns reaching from the water to the sun some- 

 what resembling the dust in a room when the light is 

 shining through it. When the air has received by this 

 process all the moisture it is capable of holding it is 

 said to be at its dew-point and the water then forms 

 in clouds and descends in rain to refresh the earth and 

 afterv/ards to be taken up again in the same manner. 



Hail is frozen water formed into balls or chunks. 

 The storms in summer are frequently accompanied by 

 hail which causes great damage when severe. The 



