THEORY of the EARTH. 211 



a fubjecl which, in another view, has appeared as the work of 

 chance, or as abfolute diforder and confufion. 



To acquire a general or comprehenfive view of this mecha- 

 nifm of the globe, by which it is adapted to the purpofe of be- 

 ing a habitable world, it is neceflary to diflinguiih three dif- 

 ferent bodies which compofe the whole. Thefe are, a folid bo- 

 dy of earth, an aqueous body of fea, and an elaflic fluid of air. 



IT is the proper fhape and difpofition of thefe three bodies 

 that form this globe into a habitable world ; and it is the man- 

 ner in which thefe constituent bodies are adjufted to each other, 

 and the laws of action by which they are maintained in their 

 proper qualities and refpeclive departments, that form the 

 Theory of the machine which we are now to examine. 



LET us begin with fome general fketch of the particulars 

 now mentioned. 



iy?, THERE is a central body in the globe. This body fup- 

 ports thofe parts which come to be more immediately expofed to 

 our view, or which may be examined by our fenfe and obferva- 

 tion. This firft part is commonly fuppofed to be folid and in- 

 ert ; but fuch a conclufion is only mere conjecture ; and we 

 {hall afterwards find occafion, perhaps, to form another judg- 

 ment in relation to this fubject, after we have examined ftriclly, 

 upon fcientific principles, what appears upon the furface, and 

 have formed conclufions concerning that which muft have been 

 tranfacted in fome more central part. 



idly^ WE find a fluid body of water. This, by gravitation, 

 is reduced to a fpherical form, and by the centrifugal force of 

 the earth's rotation, is become oblate. The purpofe of this 

 fluid body is eflential in the conftitution of the world j for, be- 

 fides affording the means of life and motion to a multifarious 

 race of animals, it is the fource of growth and circulation to 

 the organized bodies of this earth, in being the receptacle of 

 ihe rivers, and the fountain of our vapours. 



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