30 CLOUDS. 



The wonderful variety of colours displayed 

 by the clouds, arises from the different ways 

 in which the sun's light is reflected among them. 

 Many of the clouds rise to the height of fifteen 

 miles from the surface of the earth ; but their 

 general height is not above a'mile. 



Questions. 



By what is the globe of the earth surrounded ? 



What general name is given to the air and the vapours 

 which it contains ? 



What is calculated to be the pressure of the atmosphere 

 upon a man's body ? 



How is this enormous pressure counteracted ? 



To what height is the atmosphere supposed to extend ? 



What is produced by the vapours that rise from the earth 

 into the atmosphere 1 



What is wind 1 



What effect is produced upon the air by heat? 



What is the consequence of the air being rendered lighter ? 



What do we call the agitations caused in the air 1 



When the wind is violent what is it called ? 



What name do we give to the most furious winds ? 



What are their effects ? 



At what rate does a high wind move ? 



What is the velocity of the wind in a hurricane? 



From what does dew arise 1 



How is dew formed ? 



When the dew is frozen what is it called ? 



Of what do fogs consist ? 



Where are fogs most frequent? 



When are they most common ? 



How are clouds formed ? . 



Where are they produced in greatest abundance ? 



What winds bring most clouds to this country ? 



