386 THE CHEMISTRY OF CREATION. 



inclination ; sometimes, and particularly near 

 precipitous coasts, the bottom cannot be reached 

 within a few hundred yards of the rocks. The 

 one would appear as a gently-descending plain, 

 the other as an abrupt,, precipitous mountain 

 of great elevation. It must not, however, be 

 supposed that no limit exists to its profundity, 

 or that, except in the imagination of poets, it is 

 without a bottom. In all probability its depth 

 is only a fourth or a fifth part of that assigned 

 to the air; the greatest hollows being supposed 

 not to be deeper than from twelve to thirteen 

 miles, or thereabouts. 



The pressure of the atmosphere is greatest 

 on the surface of the earth. Not so with the 

 ocean. We must not forget that on the sur- 

 face of the earth we are at the bottom of 

 the aerial sea ; while, on the contrary, we are 

 at the top, so to speak, of the sea of waters. 

 Hence, as we descend into the ocean, the super- 

 incumbent pressure increases in proportion to 

 the depth attained. How vast must this pres- 

 sure become at the depth of eight or ten miles, 

 when we reflect that the pressure even of such 

 a light body as our air, equals on the earth 

 15 Ibs. on the square inch, water when per- 

 fectly pure being 815 times heavier than air! 

 Experiments upon this subject have often been 

 made. It lias been common to sink bottles full 



