154 THE OCEAN. [Book VT. 



is said to be high water at about 6^ ; the diiFerenee, 

 nine or three hours, is anoraalous — made so, probably, 

 by a derivative tide, or by a mistake.' ^ But the 

 tide which reaches Kamtschatka at 6^ must, out in 

 the ocean, have then advanced considerably farther 

 on its eastward course, and therefore the difference of 

 3^ between Kamtschatka and Vancouver's Island does 

 not appear improbable. 



'High water takes place at one time (within an 

 hour) all along the east coast of Africa ' ^ : — according 

 with the tide moving westwards through the equatorial 

 resrions of the Indian Ocean. 



o 



The paper by Admiral Fitzroy, from which all 

 the foregoing facts have been quoted, was written for 

 the purpose of showing how incompatible the actual 

 movements of the tides are with the theory which 

 supposes the tides of the Atlantic Ocean to be caused 

 by simply derivative waves branching off from a 

 wave rolling through the Great Southern Ocean. 



PART II. 



THE EQUILIBRIUM OF THE TIDES. 



That the tidal undulations — rolling westwards in 



the equatorial regions, and eastwards in the temperate 



zones — counterbalance each other, and thus preserve 



the equilibrium of the ocean as a whole, as regards 



• P. 376. 2 p, 385. 



