EECEEATIVE SCIENCE. 



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all reducible to upheavals of the earth, rum- 

 blings and explosions, ejections of carbonic 

 acid, fiery torrents of lava, cinders, and mud, 

 with accompanying thunder and lightning. 

 The last-named phenomena are extrajudicial 

 in character ; they are merely the result of 

 the atmospheric disturbance consequent on 

 the escape of great heat from the earth, just 

 as the burning of an American forest causes 

 thunder and rain. The connection that ap- 

 parently exists, too, between neighbouring 

 craters is strongly confirmed by the fact 

 that in every distinct volcanic locus but one 

 crater is usually active at a time. Since 

 Vesuvius has resumed his activity, the nume- 

 rous volcanic vents on the other side of the 

 bay have sunk into comparative inactivity ; 

 for ancient writers, who are silent respecting 

 the former, speak of the mephitic vapours of 

 the Lake Avernus as destructive to animal ex- 

 istence, and in earlier days than these Homer 

 pictures the Phlegrean Fields as the entrance 

 to the infernal regions, placed at the limits 

 of the habitable world, unenlightened by risr 

 ing or setting sun, and enveloped in eternal 

 gloom. 



If this connection be admitted, as we 

 think it must, from the geographical distri- 

 bution of the Plutonic loci, the parallel dis- 

 position of all the great granitic groups, the 

 association of volcanic vents in distinct clus- 

 ters, and the pyrogenous nature of the soil 

 surrounding them, we have to ask what indi- 

 cations do the products of upheaval afibrd in 

 confirmation of a chemical agency P There is 

 nothing in the felspar, mica, and quartz of the 

 old granite, or in the tuff, puzzola, or pumice of 

 modern volcanoes, to indicate local chemical 

 action, or to show that the combustion of 

 certain materials inter se gave rise to the con- 

 vulsions that ejected them. And yet, when 

 such enormous masses are ejected, sufiicient 

 in some places to construct great island- 

 peaks and chains of hills in the sea, and in 

 others to form enormous cones of granite, 

 pumice, and modern lavas, we may reason- 



ably expect to find in the abundance of 

 material some of the traces of their origm. 



Various chemical explanations of volcanic 

 energies have been hazarded, and numerous 

 natural affinities of bodies suggested as causes 

 sufficient to produce the effects ; but if such 

 wonderful outbreaks of fire and mechanical 

 force are owing to the flowing of water over 

 beds of potassium, or the rapid absorption of 

 oxygen by vast bodies of metals, where are 

 the resultant oxides of these inflammable 

 bases P Where, indeed, the products of any 

 purely inflammatory action brought about by 

 chemical means? Such questions may be 

 asked, and the only answer to be given is, that 

 such resultant products are not to be found. 

 Here, then, we have assigned us a cause 

 which produces no visible effect, for it must 

 be acknowledged, by the warmest defender of 

 the chemical theory, that the sulphur and 

 sulphates, the borax and iron, occasionally 

 found in volcanic disjecta, are so trivial in 

 quantity, compared with the other masses, as 

 to be worthless in support of an hypothesis ; 

 nor is it possible to escape the conclusion, 

 that if such products were formed they must 

 come within our occasional observation, either 

 from being cast forth in connected masses, or 

 brought away by the huge torrents of molten 

 rock with which we are so familiar. 



The conclusion is therefore inevitable, 

 that to account for the general distribution 

 all over the earth of volcanic vents — to account 

 also for their similarity of action and pro- 

 ducts — their enormous power and seeming in- 

 exhaustibility — their extensiveness of action in 

 their respective sites — the continuance of their 

 energies during countless years, and the in- 

 cessant burning day and night, from year to 

 year, of such craters as Stromboli; and lastly, 

 though not leastly, the apparent inefficiency 

 of external circumstances in controlling their 

 operations, eruptions happening beneath the 

 sea as beneath the land, in the frigid as in the 

 torrid zone — to account for these and many 

 less striking phenomena, we must seek for 



