GREEK IDEAS OF VULCANISM. 557 



by movements of the underlying support of the earth's crust, the next 

 to expound their origin was Anaximander, always supposing that the 

 disciple of Thales has not been confused with some later writer in the 

 following passage from Ammianus (xvii. 7, 12) : 



Anaximander says that the earth when burnt up by excessive heat and 

 drought, and also after excessive rains, opens larger fissures than usual, which 

 the upper air penetrates with great force and in excessive quantities, and the 

 earth, shaken by the furious blasts which enter those fissures, is disturbed to 

 its very foundations; for which reason these fearful events occur either during 

 periods of dryness, or else after unusually severe rainstorms. And for this 

 reason the ancient poets and theologians gave Neptune the name of Earth- 

 shaker, since he presided over the moist element. 



Neither Anaximander, Archelaus nor Xanthus is mentioned by 

 Aristotle in connection with earthquakes or volcanoes, although their 

 opinions have been preserved by other writers. Briefly, the two leading 

 theories before Aristotle's time to account for seismic movements were 

 these: The first, which is attributed to Anaximines, referred them to 

 fractures in the earth's crust which were produced by its passing 

 through a process of drying, after having been previously saturated 

 with moisture. The other was that of Anaxagoras, who believed that 

 they were caused by the fiery elements of the ether, as well as by con- 

 fined masses of water, which had penetrated into the interior of the 

 earth, and were struggling to escape thence. In a modified form of 

 the same theory, Democritus and Archelaus attached special significance 

 to confined air as a cause of earthquakes, and this agency was still 

 further insisted upon by Aristotle. 



It will be noted that both of these theories contain potential germs 

 of suggestion. That of Anaximines, according to which the crust caves 

 in, owing to the splitting of underlying rocks after periods of extreme 

 dryness, foreshadows the modern contraction hypothesis. Excluding, 

 as this view does, the idea of any connection between seismic and vol- 

 canic disturbances, the later theory of Anaxagoras directly favors it; 

 and in the hands of the great Stagyrite this connection became the 

 leading feature in the discussion of the question. According to 

 Aristotle, both forms of subterranean disturbances were due to the 

 action of winds (or gases, as we should probably say) which were con- 

 fined beneath the earth's surface and were endeavoring to find a vent. 

 The element of fire which appears in volcanic eruptions was explained 

 at the result of vapors becoming rarefied and thereupon igniting. Im- 

 perfect as this theory may seem, it subsequently met with general ac- 

 ceptance and after slumbering for many centuries, was revived by 

 Cecco d'Ascoli, contemporary of Dante, when Italy again caught the 

 reflection of Greek learning. Posidonius, Strabo, Ovid, Pliny, and the 

 unknown author of ' iEtna ' whom some have sought to identify with 

 Lucilius junior, all were influenced by Aristotle's view. Ovid, for 

 instance, in his description of the upheaval of the promontory of 



