558 POPULAR SCIENCE MONTHLY. 



Methana* in the Argolis peninsula, which happened about the year 

 282 B.C., likens the process to the inflation of a bladder: " The earth," 

 he says, " became distended by the force of impregnated vapor like a 

 bladder filled with air, or like the skin of a goat." A like influence is 

 betrayed also in the beautiful poem of Lucretius, where the following 

 explanation is offered (VI., 639-702) : " iEtna emits its flames in this 

 way: caverns of rock run under it, full of wind which heats first 

 itself and then the rocks with which it comes in contact, and then 

 bursts out with flame, ashes, smoke and huge stones. Again, caverns 

 reach from the sea to the mountain; through these pass from the sea 

 both water and wind mixed; this wind and water force up flame and 

 rocks and clouds of sand." 



By more careful observation of these occurrences it was further 

 established that volcanoes served as a vent in consequence of which the 

 frequency and violence of earthquake shocks were diminished. Thus, 

 Strabo remarks that the destructive shocks to which the island of 

 Euboea was subject, ceased when an eruption took place in the plain 

 of Lelanto, near the city of Chalcis.f Again, he explains the cessation 

 in Southern Italy of any such convulsions as were supposed to have 

 separated Sicily from the mainland by the formation in that region 

 of cones of eruption, like those of the Lipari Islands. J Elsewhere he 

 uses the term of ' breathing holes ' in reference to such cones. That 

 he had a clear understanding of this feature is evident from the follow- 

 ing passage : 



But now these mouths being opened, through which the fire is drawn up, 

 and the ardent masses and water poured out, they say that the land in the 

 neighborhood of the Straits of Sicily rarely suffers from the effects of earth- 

 quakes; but formerly all the passages to the surface being blocked up, the fire 

 which was smouldering beneath the earth, together with the vapor, occasioned 

 terrible earthquakes, and the regions being disturbed by the force of the pent-up 

 winds, sometimes gave way, and being rent, received the sea, which flowed in 

 from either side; and thus were formed both this strait and the sea which sur- 

 rounds the other islands in the neighborhood. 



Notwithstanding our indebtedness to Strabo for many interesting 

 details concerning Etna and other volcanic districts, to say nothing of 

 his luminous remarks on the elevation and subsidence of land-masses, 

 he does not seem to have advanced any original explanations of physical 

 phenomena, but merely to have re-echoed those of his predecessors, fore- 

 most of whom were Aristotle and Posidonius. Indeed, it is no exagger- 

 ation to say that nearly all of Strabo's physiographic ideas were in- 

 spired directly by these marvelously keen investigators.* The in- 



* Metam., XV., 296-306. Pliny ('Nat. Hist.,' II., 192) also gives his ad- 

 herence to the same view. 



t Strabo, VI., 1, 6. 

 t Ibid., I., 3, 16. 



* Compare, for instance, the estimates given by M. Dubois, in his ' Examen 

 de la Geographie de Strabon ' (Paris, 1891), and S. Sudhaus, in his interesting 

 essay on 'iEtna' (Leipzig, 1901). 



