THE 



PHYSICAL GEOGRAPHY OF THE SEA, 

 AND ITS METEOROLOGY. 



CHAPTER 1. 



1-68. — THE SEA. AXD THE ATMOSPHERE. 



§ 1. The two oceans of air and water. — Our planet is invested with 

 two great oceans ; one visible, the other invisible ; one is under- 

 foot, the other overhead; one entirely envelops it, the other 

 covers about two-thirds of its surface. All the water of the one 

 v>'eighs about 400 times as much as all the air of the other. 



2. Their meeting.- — It is at the bottom of this lighter ocean 

 where the forces which we are about to study are brought into 

 play. This place of meeting is the battle-field of nature, the 

 dwelling-place of man; it is the scene of the greatest conflicts 

 which he is permitted to witness, for here rage in their utmost 

 fury the powers of sea, earth, and air ; therefore, in treating of 

 the Physical Geography 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. Their depth. — As to their depth, we know very little more of 

 the one than of the other ; but the conjecture 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, 



B 



