THE TIDES 159 



into steam, thus liberating forces which threaten 

 to rive the globe asunder. It is, indeed, highly 

 probable that many earthquakes are caused in this 

 way, apart altogether from the dreadful damage done 

 by the mighty mass of displaced water rushing back 

 upon the land, and overwhelming it, as the breaking 

 loose of a dammed up reservoir drowns the whole valley 

 beneath. 



Probably, however, enough has been said upon this 

 part of the subject, especially as we are at the close of 

 the chapter ; and it would be entirely wrong to leave 

 the reader with the terrible impression of the earth- 

 quake wave upon his mind. These incidental happen- 

 ings are, of course, calamities of the highest order, but 

 they bear no closer relation to the altogether calm 

 and beneficent action of the regular tides than does 

 the hurricane bear to the gentle zephyr or the steady 

 faithful Trade Wind. Drawn by the persistent suasion 

 of our satellite, the sea performs with beautiful 

 regularity its invaluable task of cleansing the shores, 

 which, left without such ablutions, or with only 

 irregular visitations of the sparkling flood, would, in 

 a very large number of cases, be entirely pestilential. 

 It is one of the most important ministrations to earth 

 of the benevolent sea. 



