GREAT NATURAL DIVISIONS OF THE EARTH. 



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Geography, in the widest acceptation of the term, embraces a description of the true 

 figure and motions of the earth the aspect of the superficies, and the mode in which its 

 respective parts have been arranged ; with the extent, population, resources, knowledge, 

 and arts of particular localities. These are the Mathematical, Physical, and Civil branches 

 of the subject ; to the second of which the present section is devoted. It is the province 

 of the physical geographer to deal with the features of the external surface of the earth's 

 mass ; and, in strictness of meaning, this is the boundary of his department. But it is 

 customary also to treat of atmospheric phenomena and influence ; of the variations of 

 climate and temperature ; of the distribution of the different classes of organised beings ; 

 and of the causes which have determined the distribution an arrangement which it is 

 difficult to follow without trenching upon ground occupied by other sciences. It is desir- 

 able, however, to respect the boundaries which belong to the various branches of physical 

 enquiry ; and therefore, while it will be impossible to avoid touching upon the domains 

 of Geology, Botany, and Zoology, the avoidance of a trespass will be studied. 



The terrestrial surface presents us with areas of land and water constituting two great 

 Natural Divisions. The outlines of each are in a state of constant change ; but the alter- 

 ation proceeds so slowly, that apparently they are the same at present, with a few com- 

 paratively unimportant exceptions, as at the earliest date of geographical information. 

 There is a remarkable difference in the extent of these divisions. The whole area of the 

 globe includes about 197 millions of square miles, of which seven-tenths are usually given 

 as the proportion of space occupied by the waters, approaching to 1 38 millions of square 

 miles, leaving less than 60 millions for the area of the land. The distribution of the two 

 is also as unequal as their extent. If we take London to be the centre of a hemisphere, 



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