268 COSMOS. 



universe which Plato establishes in the Phsedo (p. 112 

 11 4) this co-operation is still more boldly extended to all 

 volcanic systems. The lava-streams derive their materials 

 from the Pyriphlegethon, which " after it has repeatedly 

 rolled around beneath the earth," pours itself into Tartarus. 

 Plato says expressly that the fire-vomiting mountains, wher- 

 ever such occur upon the earth, blow upwards small portions 

 from the Pyriphlegethon (" OUTO? Sea-rlv ov iTrovopa^ovai 

 Tlvpi(f)\e?ye0oi>ra, ov KOI ol pvatce? airoaTraa fiend ava<J)va{caiv t 

 oirr) av Tv^wai rrj<i 7^?"). This expression (p. 113 B.) of the 

 expulsion with violence refers to a certain extent to the 

 moving force of the previously enclosed wind, then suddenly 

 breaking through, upon which the Stagirite afterwards, in 

 the Meteorology, founded his entire theory of vulcanicity. 



According to these ancient views the linear arrangement of 

 volcanoes is more distinctly characterized in the consideration 

 of the entire body of the earth, than their grouping around a 

 central volcano. The serial arrangement is most remarkable in 

 those places where it depends upon the situation and exten- 

 sion of fissures, which, usually parallel to each other, pass 

 through great tracts of country in a linear direction (like 

 Cordilleras). Thus, to mention only the most important 

 series of closely approximated volcanoes, we find in the 

 new continent those of Central America, with their appen- 

 dages in Mexico ; those of New Granada and Quito, of Peru, 

 Bolivia, and Chili ; in the old continent the Sunda Islands 

 (the Indian Archipelago, especially Java), the peninsula of 

 Kamtschatka and its continuation in the Kurile Islands, 

 and the Aleutian Islands, which bound the nearly closed 

 Behring's Sea on the south. We shall dwell upon some of 

 the principal groups ; individual details, by being brought 

 together, lead us to the causes of phenomena. 



The linear volcanoes of Central America, according to the 

 older denominations the volcanoes of Costa Rica, Nicaragua, 

 San Salvador, and Guatemala, extend from the volcano 

 Turrialva near Cartago to the volcano of Soconusco, over 

 six degrees of latitude, between 10 9 and 16 2, in a line 

 the general direction of which is from S.E. to N.W., and 

 which, with the few curvatures which it undergoes, has a 

 length of 540 geog. miles. This length is about equal to the 

 distance from Vesuvius to Prague The most closely ap- 



