xi AIR AS CAUSE 



239 



spreading fire causes immense extents of water to 

 boil. It then by evaporation from the overflowing 

 waters shakes violently whatever it strikes. 



XII 



MANY of the greatest authorities are persuaded that i 

 earthquakes are to be attributed to air. Archelaus, 

 who is well versed in the records of antiquity, speaks 

 thus: Winds are carried down into the earth's 

 hollows and recesses. When they are all full, and the 

 atmosphere is condensed to the utmost extent, the 

 air, which continues to come in, forces and thrusts 

 the former air, and with frequent blows first com- 

 presses and then dislodges it. The air in its 2 

 endeavour to find room forces all the narrow 

 passages and tries to burst its barriers. Through 

 the struggle of the air as it seeks for an escape 

 it comes to pass that the earth is moved. This 

 explains why the approach of an earthquake is 

 preceded by still and quiet of the atmosphere ; 

 the force of the air which is wont to rouse the 

 winds is held in check in its nether abode. Even 3 

 on the present occasion of the earthquake in 

 Campania, although the season was winter, the 

 atmosphere was perfectly still and calm for several 

 days before it. 1 Well, then, did an earthquake 

 never take place when there was a wind blowing ? 

 On very rare occasions have there been two winds 

 blowing simultaneously. Still, such a thing is 

 possible, and is wont to occur. But if we admit 

 it as an established fact that two winds can be 

 in activity at one and the same time, why shouldn't 



1 The text is uncertain, and the argument down to the end of the chapter 

 rather obscure. 



