244 SEE— TEMPERATURE, SECULAR COOLING [April 20, 



for it communicates violence principally through the rapid speed. But the 

 body which goes fartherest, is that which most easily traverses all things ; and 

 it is the lightest body which is able to do this. Consequently since the 

 nature of the air itself is the lightest, it is the blast of wind which most 

 powerfully moves all bodies ; for the fire, whenever accompanied by a blast 

 of wind, produces a flame, and it is borne rapidly. Therefore is it neither the 

 water, nor the earth which is the cause of the shaking, but the blast of 

 wind, whenever the evaporation without may have again accumulated within 

 (the earth). Hence in a calm arise the most and the largest earthquakes; 

 for the exhalation being naturally continuous it follows that in general it 

 will develop with the very first agitation of the cause. Consequently either 

 from within the earth all at once, or from without by a violent impulse, 

 the whole body of vapor rushes en mass. But that some earthquakes should 

 be produced, coincident with a dominant blast of wind is not strange; for 

 we sometimes see several winds blowing together; from this circumstance, 

 whenever one strikes the earth more violently than the other while the 

 blast is blowing an earthquake takes place. But these give rise to tremors 

 of inferior magnitude, because their principle and cause are separated. 



" Now the larger number and greatest earthquakes occur by night ; those 

 of the day about noon ; for the calmest time of the day in general is at noon ; 

 for the sun then, when of the greatest power, confines the vapors to the earth ; 

 and is most powerful about mid-day ; and the nights of these days are calmest, 

 on account of the absence of the sun : consequently there arises from within 

 the earth a streaming movement like the ebb of the tides, in a sense contrary 

 to the flow of the sea without ; and this phenomenon generally develops about 

 daybreak; it is at this time that the blasts ordinarily commence to blow. If 

 therefore the force of them by chance turns quickly around, as Euripus 

 (does), on account of the mighty tides of the sea, it produces an earthquake. 



" Indeed it is about places of this kind that the mightiest of the earth- 

 quakes arise, where the sea is boisterous or the land is porous and cavernous. 

 Wherefore they occur also about the Hellespont, and about Achaia, and 

 Sicily, and about the analogous places of Euboea; for the sea seems to pass 

 through conduits under the earth. Hence also the warm springs around 

 Aidepsus are produced by the same cause. And around the aforesaid places 

 the earthquakes arise chiefly on account of the narrowness of the conduits ; 

 for the current of wind, which ordinarily blows from the land, finds itself 

 driven back by the fullness of the sea which in such places becomes violent. 



" The localities which have such caverns below thereby retaining much 

 vapor, are most shaken by earthquakes, and in the spring and the end of 

 autumn principally, and they rise both in the rainy and the dry seasons from 

 the same cause; for these are the seasons in which there is most blowing of 

 wind ; in fact both summer and winter, the one by the frigidity and the other 

 by the heat, produces calms ; the one being exceedingly cold and the other 

 exceedingly dry. 



"Moreover in the dry seasons the air is very windy; for the dryness 

 devel6ps precisely when the dry exhalation is more considerable than the 

 humidity; and in the rainy seasons the internal exhalation increases, and as 

 it finds itself intercepted in very narrow places, and violently confined in a 



