232 PHYSICAL GEOGRAPHY OF THE SEA, AND ITS METEOROLOGY. 



ranean^ some of which are filtered through soils and among mi- 

 nerals which yield one kind of salts or soluble matter, another river 

 runs through a limestone or volcanic region of country, and brings 

 down in solution solid matter — it may be common salt, sulphate 

 or carbonate of hme, magnesia, soda, potash, or iron — either or all 

 may be in its waters. Still, the constituents of sea water from 

 the Mediterranean and of sea water from the Ked Sea are quite 

 the same. But the waters of the Dead Sea have no coimection 

 with those of the ocean ; they are cut off from its channels of cir- 

 culation, and are therefore quite different, as to their components,, 

 from any arm, frith, or gulf of the broad ocean. Its inhabitants- 

 are also different from those of the high seas. " The water which 

 evaporates from the sea is nearly pure, containing but very minute 

 traces of salts. Falling as rain upon the land, it washes the soil,, 

 percolates through the rocky layers, and becomes charged with 

 saline substances, which are borne seaward by the returning cur- 

 rents. The ocean, therefore, is the great depository of everything; 

 that water can dissolve and carry down from the surface of the 

 continents ; and, as there is no channel for their escape, they of 

 com'se consequently accmnulate."* They would constantly accu- 

 mulate, as this very shrewd author remarks, were it not for the 

 shells and insects of the sea and other agents mentioned. 



467. How, therefore, shall we account for this sameness of com- 

 A general system of pouud, tliis structuTO of coral (^ 465), this stability 



circulaiion required ^ . ' . i tp • .i i j n ',• 



for the ocean. as to auimai liio lu tuo sca, but upon tne supposition 



of a general system of circulation in the ocean, by which, in pro- 

 cess of time, water from one part is conveyed to another part the^ 

 most remote, and by which a general interchange and commingling 

 of the waters take place ? In like manner, the constituents of the 

 atmosphere, whether it be analyzed at the equator or the poles, are 

 the same. By cutting off and shutting up from the general chan- 

 nels of circulation any portion of sea water, as in the Dead Sea, or 

 of atmospheric air, as in mines or wells, we can easily charge 

 either -with gases or other matter that shall very much affect its 

 character, or alter the proportion of its ingredients, and affect the 

 health of its inhabitants ; but in the open sea or open air we can do 

 no such thing. 



468. The principal agents that are supposed to be concerned in 

 Dynamical agents, giviiig circulatioii to the atmosphcre, and in preserv- 

 ing the ratio among its components, are light, heat, electricity, ani 



* Youman's Chemistry. 



