moreover, traversed,, both in the new and the old world, 

 extensive continental districts presenting the most striking 

 contrasts ; on the one hand the tropical and alpine landscapes 

 of Mexico and South America, and on the other the dreary 

 uniformity of the steppes of Northern Asia. Such oppor- 

 tunities could not fail to encourage the tendencies of a mind 

 predisposed to generalisation, and were well fitted to animate 

 me to the attempt of treating in a special work our present 

 knowledge of the sidereal and terrestrial phenomena of the 

 universe in their empirical connection. " Physical Geogra- 

 phy/' the limits of which have been hitherto somewhat vaguely 

 defined, has been thus expanded, by perhaps too bold a plan, 

 into a scheme comprehending the whole material creation, 

 or into that of a " Physical Cosmography." 



Such a work, if it would aspire to combine with scientific 

 accuracy any measure of success as a literary composition, 

 has to surmount great difficulties, arising from the very abun- 

 dance of the materials which the presiding mind must reduce 

 to order and clearness, while yet the descriptions of the varied 

 forms and phenomena of nature must not be deprived of 

 the characteristic traits which give them life and animation. 

 A series of general results would be no less wearisome than 

 a mere accumulation of detached facts. I cannot venture to 

 natter myself that I have adequately satisfied these various 

 conditions, or avoided the dangers which I have not failed 



