198 COSMOS. 



from the elevation of whole continents and mountain chains to 

 the development and effusion of gaseous and liquid fluids, of 

 hot mud, and of those heated and molten earths which be- 

 come solidified into crystalline mineral masses. Modern 

 geognosy, the mineral portion of terrestrial physics, has made 

 no slight advance in having investigated this connection of phe- 

 nomena. This investigation has led us away from the delusive 

 hypothesis, by which it was customary formerly to endeavour to 

 explain, individually, every expression of force in the terrestrial 

 globe ; it shows us the connection of the occurrence of heteroge- 

 neous substances with that which only appertains to changes 

 in space (disturbances or elevations) and groups together 

 phenomena which at first sight appeared most heterogenous ; 

 as thermal springs, effusion of carbonic acid and sulphurous 

 vapour, innocuous salses (mud eruptions) and the dreadful devas- 

 tations of volcanic mountains.* In a general view of nature all 

 these phenomena are fused together in one sole idea of the 

 reaction of the interior of a planet on its external surface. We 

 thus recognise in the depths of the earth, and in the increase 

 of temperature with the increase of depth from the surface, 

 not only the germ of disturbing movements, but also of the 

 gradual elevation of whole continents (as mountain chains on 

 long fissures), of volcanic eruptions, and of the manifold pro- 

 duction of mountains and mineral masses. The influence of 

 this reaction of the interior on the exterior is not, however, 

 limited to inorganic nature alone. It is highly probable, that 

 in an earlier world more powerful emanations of carbonic 

 acid gas, blended with the atmosphere, must have increased 

 the assimilation of carbon in vegetables, and that an inex- 

 haustible supply of combustible matter (lignites and car- 

 boniferous formations) must have been thus buried in the 

 upper strata of the earth by the revolutions attending the 

 destruction of vast tracts of forest. We likewise perceive 

 that the destiny of mankind is in part dependent on the form- 

 ation of the external surface of the earth, the direction of 

 mountain tracts and high lands, and on the distribution of 

 elevated continents. It is thus granted to the enquiring mind 



* [See Mantell's Wonders of Geology, 1848, vol. i. pp. 34, 36, 105; 

 also Lyell's Principles of Geology, vol. ii., and Daubeney, On Volcanoes, 

 2nd ed. 1848, P. II., ch. xxxii. xxxiii.] Tr. 



