Intelligence and Miscellaneous Articles. 317 



One of these hypotheses, which derives the vulcanism of the 

 earth merely from water penetrating into the glowing depths, is 

 unsuitable for such a generalization, because both the phenomena 

 in the sun and the absence of water on the moon are incompatible 

 with its presuppositions. A second hypothesis, which takes for its 

 principle the conversion of work into heat, and, in accordance with 

 Mallet's experiments, assumes that volcanic phenomena are condi- 

 tioned by the heat arising from the sinking by contraction of the 

 earth's crust, meets with a not unfounded opposition from many 

 quarters, since the quantity of heat on which this view rests is so 

 insignificant that, according to the calculation of the propounder 

 himself, it could produce in the most favourable case a rise of tem- 

 perature from 15° to 55° C. 



The assumption made use of by Nasmyth and Carpenter in order 

 to account for the eruptive formation of the lunar craters, when 

 they referred the former volcanic activity of the moon to con- 

 traction of volume in solidifying, is also improbable in itself and 

 incapable of general application. 



On the contrary, an older hypothesis, which has hitherto met 

 with but little notice, is of high importance for the explanation of 

 cosmic vulcanism. It assumes that the volcanic phenomena of the 

 earth are effected by gases and vapours which are contained ab- 

 sorbed in the supposed fluid interior of the earth, and are evolved 

 as it gradually solidifies. It is true that, as remarked by Angelot, 

 who occupied himself with the consideration of this idea, it is not 

 sufficient for the complete explanation of the earth's vulcanism ; 

 but it completes the explanation which is based upon the penetration 

 of w T ater into the depths in the most important points, especially in 

 its chemical aspect ; and, besides, it admits of application to the 

 other heavenly bodies, in that it represents their eruptive pheno- 

 mena as a consequence of progressive cooling. 



This view has moreover the advantage over its competitors, that 

 it is already contained in that more general hypothesis set up by 

 Kant and Laplace for the purpose of making intelligible the forma- 

 tion of the solar system, If the production of the heavenly bodies 

 be conceived as an aggregation into spheres of such materials as 

 are represented in the earth, it must be admitted that the formed 

 globes of glowing liquid contain absorbed matters which may be 

 evolved from them in a gaseous form and occasion eruptions. 



Observations on many glowing liquid bodies, such as volcanic 

 lavas, east iron, melted copper and silver, &c, show that, especially 

 under a higher pressure, they are capable of absorbing large 

 amounts of gaseous substances, and giving them out again on 

 solidifying. Accordingly those materials which, according to 

 modern views, are imagined in the interior of the earth and in the 

 neighbouring heavenly bodies, are of such a nature as to evolve 

 masses of gas on cooling. 



The application of the above to the sun is self-evident. Meteors 

 are derived from very small stars, which in their rapid cooling fall 

 into eruption, and therewith are in part or wiiolly disintegrated. 

 The surface-features of the moon can in like manner be traced 



