^ 



Hi 





e 



o 



5. 

 kef 



lav; 





Ltion 



that 



mi 



that 



now 



! 



rever 



saose 



i, and 



it the 

 i the 



te oi 



•date 

 >iiion- 



bitis 



3 rock 



nainS' 

 lough 



. 



tmay 



f the 



ftb« 



o 







Ch. XII.] 



DIFFUSION OF HEAT OVER THE GLOBE 



235 



ma ke a near approximation to a true theory. But the effect 

 f former variations in the heat and cold of the different 

 seasons in the year, caused by the precession of the equinoxes, 

 combined with the revolution of the apsides, and still more 

 by variations in the excentricity of the earth's orbit, will have 



. . more dominant 

 Should doubts and 



influence of geographical conditions. 



obscurities still remain, they should be ascribed to our limited 



Natur 



her economy 



They should stimulate us to farther research, 

 not tempt us to indulge our fancies respecting imaginary 

 changes of internal temperature, or the unsettled state of the 

 surface of a planet before it was prepared for the habitation 



of living beings. 

 Diffusion of h 



— In considering the laws 



must 



remar 



be careful, as Humboldt well 

 climate of Europe as a type of the temperature which all 

 countries placed under the same latitude enjoy. The physi- 

 cal sciences, observes this philosopher, always bear the im- 

 press of the places where they began to be cultivated ; and 



as, m 



made 



volcanic phenomena to those of Italy, so in meteorology, a 

 small part of the old world, the centre of the primitive 

 civilisation of Europe, was for a long time considered a type 



- « •-ill 



mi 



referred. But this region, constituting only one-seventh of 

 the whole globe, proved eventually to be the exception to the 



general rule. 



same 



eolo- 



gist to be on his guard, and not hastily to assume that the 

 temperature of the earth in the present era is a type of that 



far 



which most usually obtains, since he contemplat 

 mightier alterations in the position of land and sea, at diffe- 

 rent epochs, than those which now cause the climate of 



countr 



parallels of latitude. 



warmth 



in the atmosphere and in the waters of the ocean, are neither 



I 



