THE 



PHYSICAL GEOGRAPHY OF THE SEA, 

 AND ITS METEOPiOLOGY. 



CHAPTEE I. 



1-68. THE SEA AND THE ATMOSPHERE. 



§ 1 . OuE planet is invested with two great oceans ; one visible, 

 The two oceans of the other invisible ; one is imderfoot, the other over- 

 air and water. head ; one entirely envelops it, the other covers 

 about two thirds of its surface. All the water of the one weighs 

 about 400 times as much as all the air of the other. 



2. It is at the bottom of this lighter ocean where the forces 

 Their meetmg. whicli WO are about to study are brought into play. 



This place of meeting is the battle-field of natm^e, the dvcolling- 

 place of man ; it is the scene of the greatest conflicts which he is 

 permitted to witness, for here rage in their utmost fiu-y the povrers 

 of sea, earth, and air ; therefore, in treating of the Physical Geo- 

 graphy of the sea, we must necessarily refer to the phenomena 

 which are displayed at the meeting of these two oceans. Let us, 

 therefore, before entering either of these fields for study, proceed 

 first to consider each one in some of its most striking characteristics. 

 They are both in a state of what is called unstable equilibrium ; 

 hence the currents of one and the winds of the other. 



3. As to their depth, we know very little more of the one than 

 Their depth. of tlic othoT ; but the conjectiu^e that the average 



depth of the sea does not much exceed four miles is probably 

 as near the truth as is the commonly received opinion that the 

 height of the atmosphere does not exceed fifty miles. If the air 

 were, like water, non-elastic, and not more compressible than this 



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