VOLGA N'OES. 213 



Tlie geoirraphicai distribution of the volcanoes wliich have 

 been ill a state of activity during historical times, the great 

 number of insular and littoral volcanic mountains, and the oc- 

 casional, although ephemeral, eruptions in the bottom of the 

 sea, early led to the belief that volcanic activity was connect- 

 ed with the neighborhood of the sea, and was dependent upon 

 it for its continuance. " For many hundred years," says Jus- 

 tinian, or rather Trogus Pompeius, whom he follows,* " j^tna 

 and the ^Eolian Islands have been burning, and how could 

 this have continued so long if the lire had not been fed by the 



* " Accedunt viciiii et perpetui yEtnte montis igues et' insularum 

 iEolidum, veluti ipsis uudis alatur inceudium ; neque euim aliter durare 

 tot seculis tautus ignis potuisset, nisi humoris nutrimentis aleretur." 

 (Justin, Hist. Philijpp.i i%'., i.) The volcanic theory with which the 

 physical description of Sicily here begins is extremely intricate. Deep 

 strata of sulphur and resin ; a very thin soil full of cavities and easily 

 fissured ; violent motion of the waves of the sea, wliich, as they strike 

 together, draw down the air (the wind) for the maintenance of the fire : 

 such are the elements of the theory of Trogus. Since he seems from 

 Pliny (xi., 52) to have been a physiognomist, we may presume that his 

 numerous lost works were not confined to history alone. The opinion 

 that air is forced into the iuteiior of the earth, there to act on the vol- 

 canic furnaces, was connected by the ancients with the supposed influ- 

 ence of winds from diiFerent quarters on the intensity of the iires burn- 

 ing in iEtna, Hiera, and Stromboli. (See the remarkable passage in 

 Strabo, lib. vi., p. 275 and 276.) The mountain island of Stromboli 

 (Strongyle) was regarded, therefore, as the dwelling-place of iEolus, 

 "the regulator of the winds," in consequence of the sailors foretelling 

 the weather from the activity of the volcanic eruptions of this island. 

 The connection between the eruption of a small volcano with the state 

 of the barometer and the direction of the wind is still generally recog- 

 nized (Leop. von Buch, Descr. Phys. des lies Canaries, p. 334 ; HoiT- 

 niann, in Poggend., Annalen, bd. xxvi., s. viii.), although our present 

 knowledge of volcanic phenomena, and the slight changes of atmos- 

 phferic pressure accompanying our winds, do not enable us to offer any 

 satisfactory explanation of the fact. Bembo, who during his youth was 

 brought up in Sicily by Greek refugees, gave an agreeable narrative of 

 his wanderings, and in his j^tna Dialogus (written in the middle of 

 the sixteenth centur}') ads'ances the theory of the penetration of sea 

 water to the very center of the volcanic action, and of the necessity of 

 the proximity of the sea to active volcanoes. In ascending ^Etua the 

 following question was proposed : " Explana potius nobis quae petimus, 

 ea incendia unde oriantur e': orta quomodo perdurent. In omni tellure 

 iiuspiara majores fistulae aut meatus ampliores sunt quam in locis, qua) 

 vel mari vicina sunt, vel a mari protinus alluuntur : mare erodit ilia 

 facillime pergitque in viscera terras. Itaque cum in aliena regna sibi 

 viam faciat, ventis etiara facit; ex quo fit, ut loca quaeque maritima 

 raaxime terra) motibus subjecta sint, parum mediterranea. Habea 

 quum in sulfuris venas venti furentes inciderint, unde incendia oriantur 

 ^tnae tu^ie. Vides, quoe mare in radicibus habeat, qua? sulfurea sit. 

 qucfi cavernosa, qua) a mari aliquando perforata ventos admiserit apstu- 

 antes, per quos iJonea flamn'ae matei'ies incenderetur." 



