206 THE PHYSICAL GEOGRAPHY OF THE SEA. 



ocean at two miles, and its average saltness at 3^ per cent., it ap- 

 pears that there is salt enough in the sea to cover to the thickness 

 of one mile an area of seven millions of square miles. Admit a 

 transfer of such a quantity of matter from an average of half a 

 mile above to one mile below the sea level, and astronomers will 

 show by calculation that it would alter the length of the day. 



These seven millions of cubic miles of crystal salt have not 

 made the sea any fuller. All this solid matter has been received 

 into the interstices of sea water without swelling the mass ; for 

 chemists tell us that water is not increased in volume by the salt 

 it dissolves. Here is therefore started up before us an economy 

 of space calculated to surprise even the learned author himself of 

 the "Plurality of Worlds." 



578. There has been another question raised which bears upon 

 what has already been said concerning the offices which, in the 

 sublime system of terrestrial arrangements, have been assigned to 

 the salts of the sea. 



579. On the 20th of January, 1855, Professor Chapman, of the 

 University College, Toronto, communicated to the Canadian Insti- 

 tute a paper on the " Object of the Salt Condition of the Sea," 

 which, he maintains, is " mainly intended to regulate evapora- 

 tion.'^'' To establish this hypothesis, he shows by a simple but 

 carefully conducted set of experiments that, the Salter the water, 

 the slower the evaporation from it ; and that the evaporation which 

 takes place in 24 hours from water about as salt as the average of 

 sea water is 0.54 per cent, less in quantity than from fresh water. 



"This suggestion and these experiments give additional interest 

 to our investigations into the manifold and marvelous offices 

 which, in the economy of our planet, have been assigned by the 

 Creator to the salts of the sea. It is difficult to say what, in the 

 Divine arrangement, was the main object of making the sea salt 

 and not fresh. Whether it was to assist in the regulation of cli- 

 mates, or in the circulation of the ocean, or in re-adapting the 

 earth for new conditions by transferring solid portions of its crust 

 from one part to another, and giving employment to the corallines 

 and insects of the sea in collecting tliis solid matter into new 

 forms, and presenting it under different climates and conditions, 



