90 THE SEA. 



by Captain George Wilson, of Milton, the famous oyster place, near Sitting-bourne, 

 in Kent, and which is also famous for its divers. It is principally, however, to the 

 names of the vessels concerned that attention is directed. The United Kingdom was run 

 down by the Queen of Scotland ! 



CHAPTER VIII. 

 THE OCEAN AND SOME OF ITS PHENOMENA. 



The Saltness of the Sea Its Composition Tons of Silver in the Ocean Currents and their Causes The Great Gulf 

 Stream Its Characteristics A Triumph of Science The Tides The Highest Known Tides and Waves 

 Whirlpools The Maelstrom A Norwegian Description Edgar Allan Poe and his Story Rescued from the 

 Vortex The "Souffleur" at the Mauritius The Colour of the Sea Its Causes The Phosphorescence of the Ocean 

 Fields of Silver Principally Caused by Animal Life. 



MANY features and phenomena of the ocean have been incidentally noted in the foregoing 

 pages; but there are points, hitherto untouched, which deserve our attention. 



Its saltness is due, not merely to the presence of chloride of sodium, or what we call 

 common salt, but to a large number of other minerals, including the chlorides of magnesium 

 and potassium, the sulphates of magnesia and lime, carbonate of lime, suphuretted hydrogen, 

 bromide of magnesia, hydrochlorate of ammonia, iodine, iron, copper, and even silver, 

 varying in proportion according to locality. The copper plates of a ship examined at 

 Valparaiso showed unmistakable traces of silver deposits. Calculations have been made 

 showing that the ocean contains 2,000,000 tons of silver. In 1,000 grains of sea-water 

 there are thirty-eight grains of these ingredients and some little organic matter. The 

 saltness of the sea is generally greater towards the poles, but to this statement there are 

 exceptions. In parts of the Irish Channel the water contains salts equal to the fortieth 

 of its weight, the saline matter rising to one-sixteenth of its weight off the coast of Spain. 

 In many places the ocean is less salt at the surface than at the bottom. Its saltness 

 increases its density and its buoyancy. 



Maury, a recognised authority, finds in the saline pi'operties of the sea one of the principal 

 forces from which the currents in the ocean proceed. " The brine of the ocean," says he, 

 " is the ley of the earth ; from it the sea derives dynamical powers, and the currents 

 their main strength." Let us suppose a long tank or, say, swimming-bath, divided in the 

 middle by a water-tight wall, on one side of which should be fresh and on the other salt 

 water, at equal levels. It is obvious that were the division removed the w r aters would not 

 stand side by side as before, for the denser water would have a tendency not merely to 

 mingle with the lighter, but to form a current under it. So salt waters of different 

 densities. 



11 The ocean," says Figuier, ' c is a scene of unceasing agitation ; ' its vast surface 

 rises and falls,* to use the image suggested by Schleiden, ' as if it were gifted with a 

 gentle power of respiration ; its movements, gentle or powerful, slow or rapid, are all 

 determined by differences of temperature/ '' Heat increases its volume, and therefore 



