xxin ACTION OF AIR 255 



undermines the earth. That is the reason why 

 land over against the sea is most frequently 

 harassed by earthquakes ; and hence it is that 

 Neptune has been assigned this power of moving 

 the earth. 1 Any one who has learned the elements 

 of Greek knows that he is called among the Greeks 

 Earthshaker 



XXIV 



I SHALL be ready to allow that air is the cause of i 

 this form of destructive earthquake. But I shall 

 have some criticism to offer as to the method by 

 which it enters the ground. Does it enter by 

 fine openings that the eye cannot detect, or by 

 larger and more evident ones ? Does it come from 

 the depths of the earth, or does it pass through 

 the surface too ? The last-mentioned view seems 

 inconceivable. In our bodies the skin keeps out 

 air, which finds no entrance except that through 

 which it is inhaled. And even when taken in by 

 us, it cannot settle except in the looser portion of 

 the body. It does not remain among the sinews 2 

 or muscle, but in the bowels and the open vessels 

 of our internal organs. The same arrangement may 

 be suspected in regard to the earth's interior from the 

 very fact that the movement in an earthquake is not 

 on the surface of the earth or about the surface, but 

 beneath in the lowest parts. A proof of this is that 

 seas of immense depth are tossed up, no doubt 

 from the movement of the ground over which they 

 spread. It is therefore probable that the earth 3 

 is moved in its depths, and that the air is formed 



1 The usual reading, marts = sea, contradicts the argument ; it cannot 

 surely be right. 



