VARIETIES OF THUNDER 75 



XXVII 



SOME writers have distinguished different kinds i 

 of thunder, saying there was one kind with a deep 

 growl like that which precedes an earthquake, 

 when the wind moans and tries to burst its prison 

 walls. Let me tell you how they suppose this 

 kind of thunder to arise. When the clouds have 

 enclosed air, it rolls through their cavernous depths 

 and emits a hoarse, regular, continuous sound like 

 bellowing. So also when that quarter of the 

 heavens is charged with moisture, its exit is pre- 

 vented until the thunder begins. Therefore, thunder 2 

 of this kind is a sure sign that rain is to follow. 

 There is another kind, which is sharp, and it might 

 be described more accurately as a crackling than 

 as a regular sound ; it resembles the report one 

 hears when a bladder is burst over some one's 

 head. Such thunder is the result of the breaking 

 up of a densely massed cloud and the release of 

 the air by which it was inflated. This is appropri- 

 ately named a peal, sudden and violent. When it 

 occurs, people collapse and are sometimes literally 

 frightened to death by it ; others retain life, but are 

 dazed and completely lose their wits : we call them 

 thunder-struck, for that sound in the heavens has 

 quite unhinged their minds. This sound may also 3 

 be produced by the atmosphere shut up in a hollow 

 cloud being rarefied, merely through motion, and 

 expanded. By and by in seeking more room for 

 itself it resounds against the walls that envelop it. 

 In fact, is it not just similar to the applause given 

 out by the clapping of the hands? only, when the 



