60 COSMOS. 



considers volcanoes either as isolated, or ranged in single or in 

 double series, and extending their sphere of action to various 

 distances, either by raising long and narrow lines of rocks, or 

 by means of circles of commotion, which expand or diminish 

 in diameter in the course of ages. This terrestrial portion ot 

 the science of the Cosmos describes the strife of the liquid ele- 

 ment with the solid land ; it indicates the features possessed 

 in common by all great rivers in the upper and lower portion 

 of their course, and in their mode of bifurcation when their 

 basins are unclosed ; and shows us rivers breaking through 

 the highest mountain chains, or following for a long time a 

 course parallel to them, either at their base, or at a consider- 

 able distance, Avhere the elevation of the strata of the mount- 

 ain system and the direction of their inclination correspond 

 to the configuration of the table-land. It is only the general 

 results of comparative orography and hydrography that belong 

 to the science whose true limits I am desirous of determining, 

 and not the special enumeration of the greatest elevations of 

 our globe, of active volcanoes, of rivers, and the number of 

 their tributaries, these details falling rather within the domain 

 of geography, properly so called. We would here only con- 

 sider phenomena in their mutual connection, and in their re- 

 lations to different zones of our planet, and to its physical con- 

 stitution generally. The specialities both of inorganic and or- 

 ganized matter, classed according to analogy of form and com- 

 position, undoubtedly constitute a most interesting branch of 

 study, but they appertain to a sphere of ideas having no affin- 

 ity with the subject of this work. 



The description of different countries certainly furnishes us 

 with the most important materials for the composition of a 

 physical geography ; but the combination of these differenl 

 descriptions, ranged in series, would as little give us a tru« 

 image of the general conformation of the irregular surface of 

 our globe, as a succession of all the floras of different region? 

 would constitute that M^iich I designate as a Geogra2)hy of 

 Plants. It is by subjecting isolated observations to the process 

 of thought, and by combining and comparing them, that we 

 are enabled to discover the relations existing in common be 

 tween the climatic distribution of beings and the individualitj 

 of organic forms (in the morphology or descriptive natural his- 

 tory of plants and animals) ; and it is by induction that we 

 are led to comprehend numerical laws, the proportion of nat- 

 ural families to the whole number of species, and to desig-nate 

 the latitude or geographical position of the zones in whose 



