192 PHYSICAL GEOGRAPHY OF THE SEA : 



contraction ; the evidence derived from the direction, paral- 

 lelism, and other aspects of mountain chains, as to periods of 

 contemporaneous elevation ; the influences upon climate of 

 lands elevated above the sea or depressed below it ; and 

 further, the whole history of that coral creation, by which, 

 under the slow working of microscopic forms of animal life, 

 islands and reefs are raised from the depth of the ocean, to 

 become the habitation of other and higher existences. 



We have thus far spoken of Physical Geography in its 

 largest acceptation. It has, however, of late been submitted 

 to a process of division, made needful by the multiplicity of 

 the objects it includes ; and the phrase of ( Physical Geography 

 of the Sea,' proposed by Humboldt, is the title of the first of 

 the works now before us. Under this title its author, Captain 

 Maury, of the United States navy, includes all that concerns 

 the great domain of waters over the globe ; the oceans, seas, 

 and basin lakes into which they are distributed ; their various 

 depth, temperature, and saltness ; the currents which per- 

 manently or periodically pervade them ; the phenomena of 

 the tides ; the phenomena of winds, whether constant or 

 irregular, whether the steady trade breeze, or the hurricane 

 and cyclone ; the law of evaporation belonging to different 

 latitudes of the watery world ; the less known, yet certain 

 agency of magnetic or electrical forces ; and the mutual in- 

 fluence of ocean and land in all these physical actions and 

 changes. This summary statement shows how vast and 

 various are the objects in the division of science thus pro- 

 posed. We find further reason for its adoption in the im- 

 portance of all these objects to the principles and practice of 

 navigation ; a matter of supreme weight in these days, 

 when the ocean in its every part is covered with ships; 

 shaped in new forms, moved by new forces, destined to new 

 shores, and seeking to attain by new routes the highest speed 

 of transit. Facts and phenomena, before unobserved or bar- 



