humboldt's "cosmos." 403 



treatment of a physical description of cosmical phenomena ; and 

 3. A general picture of nature ; or, in other words, a complete sketch 

 of these various cosmical phenomena. Of these three parts the 

 first has long been written, and was delivered many years ago as 

 an address on the opening of a public institution at Berlin ; but 

 has been added to and altered in some respects for the present 

 work. The rest of the volume, although not without some ap- 

 parent resemblance to a series of lectures delivered by the author 

 in 1827-8, contains little that is not specially prepared for the 

 present work. 



As an example of the mode of treatment pursued by our author 

 with reference to geological phenomena, we may here offer a 

 quotation introduced after some observations on the important 

 mutual bearing of certain remarkable facts made known by the 

 careful study of physical astronomy : — 



Just in the same way as in these astronomical conclusions, it is only by means 

 of general views of cosmical phenomena that we are enabled to perceive the 

 relation between the theory of the pendulum, so ingeniously worked out by 

 Bessel, and the condition of the material substance of our planet in its interior — 

 between the production of porphyritic rocks in lava currents on the flanks of an 

 active volcanic mountain, and the masses of granite, porphyry, and serpentine 

 which have been forced up from the deep recesses of the earth through the over- 

 lying stratified rocks, hardening, silicifying, dolomitising and crystallising them— 

 between, in fact, the elevation of conical hills and small islands by the elastic 

 force of modern volcanic action, and the formation of vast mountain chains and 

 of whole continents, — a relation, be it observed, clearly proved by means of a 

 series of admirably contrived observations made by one of the greatest of living 

 geologists, Leopold von Buch. Such a protrusion of igneous rock, elevating at 

 the same time the overlying horizontally deposited strata, accounts for the 

 presence of the fossil remains of mollusca found by myself and M. Bonpland at 

 the height of 14,000 feet above the sea, on the flanks of the Andes, allowing 

 us to suppose that they have been placed where they now are by volcanic force 

 lifting them up from their original position, and not requiring that the sea 

 should ever have washed over them at their present altitude. 



Volcanic agency, using this phrase in its most extended sense, I consider to 

 be, whether upon the earth or on its satellite the moon, the reaction by which 

 the material substances elaborated beneath the surface are lifted, from time to 

 time, above the surface. Those, however, who are not acquainted with the ex- 

 periments concerning the increase of temperature observed at increasing depths 

 beneath the earth (experiments which render it probable that granite exists in 

 a melted state at the depth of about twenty miles) can of course form no idea 

 of the cause of numerous phenomena recently observed concerning the contem- 

 poraneity of volcanic eruptions and earthquakes over a vast extent of country, 

 the uniformity of the temperature of warm mineral springs, or the difference of 

 temperature of artesian wells sunk to different depths. But this knowledge of 

 the internal temperature of the earth throws some glimmering of light upon the 

 ancient history of our planet, for it shows the possibility of a former universal 

 and tropical climate, the result of heat emanating perhaps from fissures in the 

 recently hardened and oxydised crust of our globe. It thus reminds us of a 

 condition in which the temperature of our atmosphere was dependent on the 

 heat radiating from the planet itself outwards into space, rather than on the 

 relation of the planet to a great central mass (the sun), whence alone it now ob- 

 tains warmth. 



Many indeed are the tropical productions, hidden and buried beneath the 

 surface, but discovered by the geologist, in the colder regions of the earth : — 

 coniferous trees, erect trunks of palms, tree ferns, the shells of Cephalopodous 



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