PRESENT PROBLEMS OF GEOGRAPHY 657 



tions fully occupy the place of geography, for that place is to coor- 

 dinate and correlate all the special facts concerned, so that they 

 may throw light on the plan and the processes of the Earth and its 

 inhabitants. This was clear to Carpenter in 1625, though it has been 

 almost forgotten since. 



The principles of geography on which its claims to status as a 

 science rest are generally agreed upon by modern geographers, though 

 with such variations as arise from differences of standpoint and of 

 mental process. The evolutionary idea is unifying geography, as it has 

 unified biology, and the whole complicated subject may be presented 

 as the result of continuous progressive change brought about and 

 guided by the influence of external conditions. It is impossible to dis- 

 cuss the present problems of geography without once more recapitulat- 

 ing the permanent principles. 



The science of geography is, of course, based on the mathematical 

 properties of a rotating sphere; but there is force in Kant's classifica- 

 tion, which subordinated mathematical to physical geography. The 

 vertical relief of the Earth's crust shows us the grand and fundamental 

 contrast between the oceanic hollow and the continental ridges; and 

 the hydrosphere is so guided by gravitation as to fill the hollow and 

 rise upon the slopes of the ridges to a height depending on its volume, 

 thus introducing the great superficial separation into land and sea. 

 The movements of the water of the ocean are guided in every particu- 

 lar by the relief of the sea-bed and the configuration of the coast-lines. 

 Even the distribution of the atmosphere over the Earth's surface 

 is affected by the relief of the crust, the direction and force of the 

 winds being largely dominated by the form of the land over which 

 they blow. The different physical constitution of land, water, and 

 air, especially the great difference between the specific heat and con- 

 ductivity or diathermancy of the three, causes changes in the distribu- 

 tion of the sun's heat, and as a result the simple climatic zones and 

 rhythmic seasons of the mathematical sphere are distorted out of all 

 their primitive simplicity. The whole irregular distribution of rainfall 

 and aridity, of permanent, seasonal, and variable winds, of sea climate 

 and land climate, is the resultant of the guiding action of land forms 

 on the air and water currents, disturbed in this way from their primi- 

 tive theoretical circulation. So far we see the surface forms of the 

 Earth, themselves largely the result of the action of climatic forces, 

 and constantly undergoing change in a definite direction, control 

 the two great systems of fluid circulation. These in turn control 

 the distribution of plants and animals, in conjunction with the direct 

 action of surface relief, the natural regions and belts of climate dictat- 

 ing the distribution of living creatures. A more complicated state of 

 things is found when the combined physical and biological environ- 

 ment is studied in its incidence on the distribution of the human race, 



