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CHAPTER XVII. 



ON THE RELATIVE ACTION OP THE TIDES, THE WINDS, 

 SPECIFIC GRAVITY, AND VIS-INERTUE. 



Book II. demonstrates theoretically the action of 

 vis-inertiae in the ocean, and Book V. shows that 

 movements according with those theoretical deduc- 

 tions are apparent. We will now proceed to consider 

 whether the currents which exist in the ocean may 

 not more naturally be ascribed to the action of vis- 

 inertiaj than to that of the winds, evaporation, or any 

 other current-creating forces. 



The action of the winds in causing currents, by 

 drivmg the surface-water before them, has been de- 

 scribed by Major Rennell ; and that of evaporation, 

 which, by causing differences of specific gravity, 

 tends to create currents to restore the equilibrium of 

 the ocean, has been advocated by Captain Maury. 



Major Rennell, in his work on the Currents of 

 the Atlantic, says : — ' The tides do not occasion an 

 absolute removal of water from one place to another, 

 except very near the coasts ; and even that motion is 

 very circumscribed. ' The winds (with very few ex- 

 ceptions) are to be regarded as the prime movers of 



K 9. 



