2»h COSMOS. 



Among the general subjects of contemplati< n appertaining 

 to a work of this nature, a prominent place must be given, first, 

 to the consideration of the quantity of the land raised above 

 the level of the sea, and, next, to the individual configuration 

 of each part, either in relation to horizontal extension (rela- 

 tions of Ibrm) or to vertical elevation (hypsometrical relations 

 of mountain-chains). Our planet has tvi^o envelopes, of which 

 one, which is general — the atmosphere — is composed of an 

 elastic fluid, and the other — the sea — is only locally distribu- 

 ted, surrounding, and therefore modifying, the form of the land. 

 These two envelopes of air and sea constitute a natural whole, 

 on which depend the difference of climate on the earth's sur 

 face, according to the relative extension of the aqueous and 

 solid parts, the form and aspect of the land, and the direction 

 and elevation of mountain chains. A knowledge of the recip- 

 rocal action of air, sea, and land teaches us that great me- 

 teorological phenomena can not be comprehended when consid- 

 ered independently of geognostic relations. Meteorology, as 

 well as the geography of plants and animals, has only begun 

 10 make actual progress since the mutual dependence of the 

 phenomena to be investigated has been fully recognized. The 

 word climate has certainly special reference to the character 

 of the atmosphere, but this character is itself dependent on the 

 perpetually concurrent influences of the ocean, which is uni- 

 versally and deeply agitated by currents having a totally oppo- 

 site temperature, and of radiation from the dry land, which va- 

 ries greatly in form, elevation, color, and fertility, whether we 

 consider its bare, rocky portions, or those that are covered with 

 arborescent or herbaceous vegetation. 



In the present condition of the surface of our planet, the area 

 of the solid is to that of the fluid parts as 1 : 2|ths (accord- 

 ing to Rigaud, as 100 : 270).* The islands form scarcely ^'ad 

 of the continental masses, which are so unequally divided that 

 they consist of three times more land in the northern than in 

 ihe southern hemisphere ; the latter being, therefore, pre-emi- 

 nently oceanic. From 40° south latitude to the Antarctic 

 pole the earth is almost entirely covered with water. The 

 fluid element predominates in like manner between the east- 

 ern shores of the Old and the western shores of the New Con- 

 tinent, being only interspersed with some few insular groups. 

 The learned hydrographer Fleurieu has very justly named this 



* See Transactions of the Cambridge Philosophical Society, vcl. vi. 

 Pwt ii., 1837, p. 297. Other writers have given the ratio as lOff : 284 



