RELATIONS TO OTHER SCIENCES 619 



finite relation between these other processes and the surface forms of 

 the earth; and of certain rules according to which the surface forms 

 perform definite functions. In these facts originates that compari- 

 son of the earth's surface to an organic being which has so often been 

 made since the time of Karl Ritter. In order to understand this func- 

 tional significance of the various portions of the earth's surface, we 

 may take climate as an illustrative example. 



The waters are collected in the great hollows of the earth's surface, 

 and their uninterrupted surface presents strikingly to the eye, not 

 only the contrast between a smooth, level surface, and the physical 

 surface of the earth, but also a contrast due to two different kinds of 

 surfaces which are differently affected by the warming influence of the 

 sun. We refer to contrast between continental climate and marine 

 climate, but the sea climate is not characteristic of every portion of 

 the ocean surface, and the continental climate does not distinguish 

 all portions of the land. The surface must possess a certain amplitude 

 in order to exert a climatic influence. The small islands in the ocean 

 and the majority of the lakes on the continents have the same climate 

 as their greater surrounding region. The different thermal behavior of 

 the land areas and the water areas disturbs the regular distribution of 

 atmospheric pressure which would otherwise characterize a rotating 

 spheroid with a homogeneous surface character, and calls into exist- 

 ence, in addition to the dynamic wind system, a system of terrestrial 

 winds ranging from the small land and sea breezes to the great mon- 

 soons. In this case, the relative positions of the areas, as well as their 

 extent, exerts a dynamic influence. The monsoons blow far out be- 

 yond the boundaries of the Asiatic continent, and reach even beyond 

 its great island neighbors. Finally , the vertical extent of the land-mass 

 becomes a controlling element. In ascending we notice a regular de- 

 crease of temperature, which goes on more rapidly if the elevation is 

 needle-shaped than if it covers a greater area. Although the wind 

 may blow for a considerable distance over low, flat land without los- 

 ing much of its moisture content, yet it surrenders the latter quickly 

 where a mountain range compels it to ascend. How different are 

 the climates of Europe and western North America ! yet that is only 

 because the winds blow against mountain ranges whose axes have 

 different directions. In the one case the oceanic climate, carried by 

 the winds, makes itself felt far inland; in the other case, the contin- 

 ental climate reaches far westward under the lee of the Rocky Moun- 

 tains. In meteorological processes the size and relative positions of 

 the forms of the earth's surface are not less significant than their 

 geographical latitude. Both cooperate to determine the climate of 

 the individual regions of the earth. 



The organic world of the land's surface is most intimately depend- 

 ent upon the latter's climate. It is true that a definite flora and 



