44 CELESTIAL, ATMOSPHERIC, AND 



of a spirituous vapour (wvEupa) is generated both without and 

 within it, and this vapour flows sometimes into and some 

 times out of the Earth.* To this vapour he attributes 

 certain properties, viz., an excessive degree of mobility, a 

 very rapid inherent velocity, and great tenuity and conse 

 quent penetrating power.! Neither water nor earth, he 

 says, is a cause of earthquakes, but spirituous vapour in 

 motion, when that which has been given off outwards 

 happens to flow inwards, and, for this reason, earthquakes 

 are more frequent and violent during calm weather. I In a 

 more intelligible passage, he says that earthquakes are due 

 to violent movements of spirituous vapour (wvEupa) or wind 

 (av^os) in the interior of the Earth, such vapour or wind 

 sometimes issuing forth like a hurricane. 



By comparing the dates of recorded earthquakes in 

 Britain, France, Switzerland, and other countries, it has 

 been concluded that earthquakes are more frequent in winter 

 than in summer. According to Aristotle, they were more 

 frequent in spring and autumn, because these seasons 

 favoured the generation of the spirituous vapour ; summer 

 and winter, on the other hand, were rather periods of rest, 

 the one because of its heat, and the other because of its 

 frost. 1 1 He also concluded that earthquakes were usually 

 more frequent and violent by night than by day. II 



The violence of earthquakes, in so far as it is manifested 

 in the destruction due to them, depends in no small degree 

 on the character of the geological formations of the area of 

 disturbance. Aristotle believed that earthquakes were more 

 violent and also more frequent in districts where the land 

 was porous or cavernous, or where the coast was much 

 broken.** He instances the Hellespontine territory, Achaia, 

 Sicily, and Euboea, where the sea appeared to flow into 

 narrow passages under the earth. 1 1 



It has been stated already that Aristotle s views on the 

 natural motions of the elements, fire, air, water, and earth 

 sometimes caused him trouble when he attempted to show 

 that his explanations were in agreement with the phenomena 

 he tried to explain. His explanation of the phenomena of 

 tempests, thunder, and lightning serves as an example. In 

 some difficult passages in Meteorol. ii. c. 9, ss. 2 and 3, he 



:;: Meteorol. ii. c. 8, s. 1. \ Ibid. ii. c. 8, s. 3. 



I Ibid. ii. c. 8, s. 4. Ibid. ii. c. 8, ss. 18 and 19. 



II Ibid. ii. c. 8, ss. 11 and 12. If Ibid. ii. c. 8, s. 6. 

 ** Ibid. ii. c. 8, s, 8. ft Ibid. ii. c. 8, s. 9. 



