1907. 1 



AND CONTRACTION OF THE EARTH. 245 



less space because the cavities are full of water, the stream of wind begins 

 to acquire the force for even the compression of its own bulk in this too 

 limited space; and flowing out and striking against the passages the wind 

 produces a violent earthquake; for it is necessary to bear in mind that, 

 just as in our own body, the force of the breath held within produces a 

 trembling and suffocation, so also in the earth the blast of vapor has an 

 analogous effect; and that the shocks of earthquakes are partly of the nature 

 of trembling and partly of suffocation, just as it often comes to pass after 

 urination that a kind of vibration of the body is produced, a trembling with 

 sudden drawing of the breath from without to the interior; thus arise also 

 such phenomena with respect to the earth. 



" In order to take proper account of all the influence which the blast of 

 vapor exerts, it is necessary to observe not only what takes place in the air; 

 for one can believe in the power of such things by their magnitude; but 

 also what happens in the bodies of animals; convulsions and spasms are 

 only motions of the breath, and they have such violence that often several 

 persons uniting all their efforts are unable to keep the movements of the 

 afflicted under control. Now it is necessary to bear in mind that the same 

 thing happens also in the earth, since we naturally judge the great by refer- 

 ence to the small. 



" Signs of these things, and according to our own observation, have 

 occurred in many places ; for. the shaking of the earth arising in certain 

 localities does not cease till the agitating wind has escaped freely into the 

 region above the earth like the blast of a hurricane; it is not long ago since 

 this actually happened at Heraclea in Pontus, and formerly at the island of 

 Hlera, which is one of the islands called after ^olus ; in this some earth 

 swelled up, and with a loud noise rose in the form of a hill, and having 

 finally broke forth, the mighty urging blast escaped and ejected sparks and 

 ashes, which covered the region about the Lapari islands, spread over the 

 whole land, and extended even to several cities in Italy: and at the present 

 time where this eruption occurred is still evident; and now the development 

 of fire in the earth must be held to have caused this, at the time of the first 

 outbreak, the particles being reduced to the size of the finest dust of the air. 

 Moreover, it is proved that blasts of vapor circulated beneath the earth, and 

 that this occurred at these islands; for whenever the south wind starts to 

 blow, there are first some premonitory signs of it; for places have it from 

 which eruptions occur, because the sea is already agitated far and wide; 

 and it again confines the swelling vapor within the earth, for the simple 

 reason that the sea is spread over it. 



" Accordingly it makes a noise without an earthquake, throughout the 

 open spaces of these regions (imagined as deep conduits), either because 

 the places are very vast, since above the earth they expend into immensity, 

 or because the quantity of air expelled is very small. 



" Moreover, the changes of the sun, which grows faint and dark with- 

 out clouds, and the stillness and extreme cold, which sometimes precede the 

 earthquakes occurring at daybreak are only additional signs of the afore- 

 said cause; for the sun must be obscured and darkened when the blast of 

 vapor begins to sink within the earth, for dissolving and expelling the air, 



