32 THE DEPTHS OF THE SEA. [CHAP. i. 



according to their specific weight : skeletons of men, 

 anchors and shot and cannon, and last of all the 

 broad gold pieces wrecked in the loss of many a 

 galleon on the Spanish Main ; the whole forming a 

 kind of ' false bottom ' to the ocean, beneath which 

 there lay all the depth of clear still water, which 

 was heavier than molten gold. 



The conditions of pressure are certainly very extra- 

 ordinary. At 2,000 fathoms a man would bear upon his 

 body a weight equal to twenty locomotive engines, each 

 with a long goods train loaded with pig iron. We are 

 apt to forget, however, that water is almost incom- 

 pressible, and that therefore the density of sea-water 

 at a depth of 2,000 fathoms is scarcely appreciably 

 increased. At the depth of a mile, under a pressure 

 of about 159 atmospheres, sea-water, according to the 

 formula given by Jamin, is compressed by the TIT of 

 its volume ; and at twenty miles, supposing the law of 

 the compressibility to continue the same, by only | of 

 its volume that is to say, the volume at that depth 

 would be r of the volume of the same weight of water 

 at the surface. Any free air suspended in the water, 

 or contained in any compressible tissue of an animal 

 at 2,000 fathoms, would be reduced to a mere fraction 

 of its bulk, but an organism supported through all its 

 tissues on all sides, within and without, by incom- 

 pressible fluids at the same pressure, would not 

 necessarily be incommoded by it. We sometimes 

 find when we get up in the morning, by a rise of an 

 inch in the barometer, that nearly half a ton has been 

 quietly piled upon us during the night, but we expe- 

 rience no inconvenience, rather a feeling of exhilara- 

 tion and buoyancy, since it requires a little less exer- 



