PHENOMENA OF TIDES. 



769 



Descartes and Newton each gave a theory ; the first that of the 

 pressure of the waters ; the last, that of the attraction of the 

 sun and moon upon the waters. This last theory is the one 

 generally accepted, since it has been found satisfactory in most 

 respects; yet it still has its opponents. Now, however, that 

 the telegraph has been discovered, and a means thus afforded 

 for instantaneous communication between observers at distant 

 points, it has become possible to organize a simultaneous ob- 

 servation of the tides at various places, and eventually this will 

 be done, so that the theory that the tides are caused by the at- 

 traction of the sun and moon will be entirely proved or rejected 

 according as it will be found consistent with the facts observed. 



In this connection an interesting instance of the different 

 manner in which the ancients regarded natural phenomena, 

 from that in which the moderns regard the same occurrences, is 

 found in the fear the ancients had of the two monsters Scylla and 

 Chary bdis, which were the fabled guardians of the Straits of 

 Messina. At present there are no straits in the Mediterranean 

 more frequented than those of Messina. By the soundings 

 which have been made there, these monsters had been effectu 

 ally destroyed, and the whirlpools are known to be produced 

 by the ebb and flow of the tide, causing a greater flow of water 

 than can be accommodated by the narrow channel. The width 

 of the channel is hardly two nrles, and at low tide it has often 

 been crossed on horse-back, by swimming. The rising tide 

 tends toward the north, from the Ionian to the Tyrrhenian sea, 

 and the falling tide in the opposite, direction. There is a strife 

 between these currents, and on their confines eddies are formed 

 which ships avoid, but there is no danger unless the wind blows 

 strongly against the tide. 



Besides the influence of the currents and the tides of the 



ocean in altering the configuration of the land, the sea is the 



home of innumerable forms of animal life, which are constantly 



laboring in the same direction. It has been truly said, thai 

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