276 PROGRESS OF SCIENCE IN THE CENTURY. 



twenty is merely a question of convenience; the 

 boundaries of the sciences whose right to the name 

 is seldom questioned, physics and chemistry, as- 

 tronomy and geology, biology and psychology, 

 and so on, are flexible; two or more sciences often 

 seem confluent ; and therefore it matters little wheth- 

 er we regard geography as a unified and well-defined 

 department of science, or as a combination of sciences 

 in relation to a particular problem. 



According to a definition (by Dr. H. E. Mill), 

 on which evident care has been expended, " Geog- 

 raphy is the exact and organised knowledge of the 

 distribution of phenomena on the surface of the 

 Earth, culminating in the explanation of the inter- 

 action of Man with his terrestrial environment." * 

 Dr. Mill goes on to say, " As the meeting-place of 

 the physical and the human sciences, it is the focus 

 at which the rays of natural science, history, and 

 economics converge to illuminate the Earth in its 

 relation to man. . . . The unity of geography re- 

 sults from viewing nature in the limited but still 

 general aspect of the phenomena which affect the 

 surface of the Earth." 



The geographer is concerned with the atmosphere, 

 the hydrosphere (the water-envelope), and the litho- 

 sphere (the rocky crust whether of the continents or 

 the ocean-floors). "His first business is to define 

 the form, or relief, of the surface of the solid sphere, 

 and the movements, or circulation, within the two 

 fluid spheres. The land-relief conditions the circu- 

 lation, and this in turn gradually changes the land- 

 relief. The circulation modifies climates, and these, 

 together with the relief, constitute the environments 

 of plants, animals, and men. Short of complexities, 

 * The International Geography. London, 1899. p. 2, 



