402 THE CHEMISTKY OF CREATION. 



from land. Sailors might thus frequently be 

 made aware of the existence of shoals or sand- 

 banks without the aid of the lead, were it not 

 that a number of circumstances of local origin 

 interfere with the temperature of the water 

 near land, and thus render what might other- 

 wise prove a valuable sign, far too uncertain 

 to be relied upon. It is supposed that the in- 

 fluence of the seasons is not felt by the ocean 

 below the depth of 300 feet, 



We must now advert to a remarkable fact in 

 the physical history of the ocean, and of water 

 generally. The particles of cold water, being 

 the heaviest, descend, while the lighter warm 

 particles remain on the surface. If we suppose 

 this process to continue, the ultimate result 

 would inevitably be that our lakes, and the 

 shallower parts of our seas, would soon be 

 covered with a dense solid layer of ice, which 

 would increase until they became almost choked 

 up with it. Such an altered condition of the 

 waters would rapidly affect the climate ; our 

 summers would become cold and cheerless, our 

 winters long and severe, and our climate would 

 rapidly deteriorate, until it became of almost 

 Arctic rigour. This result is obviated by a very 

 singular law observed in water as it is gradually 

 reduced in temperature. In cooling down to 

 within eight degrees of freezing point, or 32 



