1907. 



AND CONTRACTION OF THE EARTH. 248 



simply because it is too superficially proved. To understand the elevation 

 and base in such a way that all the bodies which have weight would not at 

 every place be borne to the earth, while the light bodies and the fire tend 

 upward, is indeed most absurd; for this is going contrary to the evidence 

 of our senses, which show us that the horizon of the habitable world, so far 

 as we know it, varies constantly according to the extent which we ourselves 

 change place, the earth being convex and spherical. To say that on account 

 of its mass it remains in the air, and to maintain that the trembling of the 

 earth arises when it is smitten from below upwards in its totality, is not 

 less strange. Moreover, in these considerations, Anaxagoras takes no account 

 of some circumstances which accompany earthquakes ; for not all lands, nor 

 all seasons participate in this commotion, by chance and indiscriminately. 



" Democritus indeed holds that the matter of the earth is full of water, 

 and receiving much other water from the rain storms, it is moved by this; 

 but this arises more from the inability to hold (the water) in the yawning 

 cavities, which, breaking forth violently, causes the shaking of the earth; and 

 the ground being dry and drawing forth into the empty places water escap- 

 ing from the reservoirs, gives rise to motion of sudden agitation. 



" Anaximenes, on the other hand, holds that when moistened and after- 

 wards dried out the earth is shattered to pieces, and is shaken from the 

 sinking in of fragments of the hills; from which also arises the earthquakes 

 in the dry, and likewise in the wet, seasons; for in droughts, just as is said, 

 the dry ground is cracked open, and the overmoist earth, produced by the 

 absorption of the waters, subsides. If that happens which is agreeable to the 

 theory of Anaximenes one should observe in many places the earth caving 

 in. Yet by what cause the phenomenon arises in certain places, no one 

 opinion carries extreme weight of authority relatively to others; neverthe- 

 less such a claim was put forth. 



" This explanation supposes necessarily that earthquakes always become 

 less and less powerful, and finally cease to vibrate. That which settles down 

 ought to do so naturally. Consequently if this is impossible, it is very evi- 

 dent that it can not be the true cause of the phenomenon. 



"Cap. VIII. 



" But since it manifestly is a necessity, that exhalation of vapor should 

 be produced all the time, both from the moisture and from the dryness, as 

 we have said in what precedes, it is likewise necessary that from these an- 

 tecedents earthquakes should be produced ; for in itself the earth is dry, yet 

 on account of the rains, acquires in its interior much moisture; so that having 

 been warmed by the sun, and the internal fire, largely indeed from without, 

 but also largely from within, the blast of vapor is developed ; and this blast 

 when it sometimes escapes externally flows in a continuous manner; and like- 

 wise sometimes when it escapes within the earth ; and then again it is 

 scattered. If then this can not take place otherwise, we must consider what 

 among all these bodies, is the most capable of producing the motion ; this 

 is necessarily that which naturally goes fartherest, and is most violent, but 

 especially of this latter nature. 



" Now the most violent is of necessity that which moves the most rapidly; 



