On the Level of' the Sea. 337 



the pole, would all be at the same distance from the earth's centre. 

 This would be the state of things in consequence of the laws of 

 hydrostatics, and the structure of the solid parts of the globe, 

 which presents trifling inequalities at the surface. Great inequa- 

 lities in the solid parts would disturb the sphericity of the liquid 

 surfaces. Were the chain of the Cordilleras only a hundred 

 times higher, the waters would rise on the coasts of America, on 

 the eastern as well as the western side ; and would occupy a 

 lower level on the opposite coasts, leaving the ports of France 

 dry, as well as those of Japan. 



If the earth were stationary, and formed externally of hetero- 

 geneous parts of very unequal density ; if, for example, under the 

 Atlantic Ocean, between the crust which forms its bottom, and 

 the centre of the earth, there should occur vast cavities, empty 

 or filled with substances of small density, it is evident that the 

 intensity of the attraction of gravitation would be much less on 

 the waters of the Atlantic, than those of the other seas, and that 

 then the general surface of the waters, instead of being every- 

 where spherical, would be raised in some parts, and depressed in 

 others. Thus, a heterogeneousness of substances might of itself 

 produce irregularities of form, and if to this cause there be add- 

 ed the influence of the centrifugal force, it will be seen that the 

 question becomes still more complicated. In our present state 

 of ignorance respecting the internal structure of the globe, in- 

 to which, with all our power, we are only able to penetrate to a 

 very trifling depth, the only means which we have of finding 

 the true form of the surface of the seas, are geodesical operations, 

 and observations with the pendulum. By the first of these 

 means we arrive at a knowledge of the fact, independently of 

 all hypothesis and of all explanation ; and by the other we shall 

 perhaps be able to discover some general laws of the internal 

 structure of the earth, or at least some of the local causes that 

 may alter the regularity of its surface. The equilibrium of the 

 waters depends upon the direction of gravity, and the oscilla- 

 tions of the pendulum depend upon the intensity of the same force. 

 It is difficult to discover a priori in what degree these two ele- 

 ments are connected together, and to what extent they may be 

 determined by each other ; and it is this that gives still more im- 



JULY— SEPTEMBER 1828. Y 



