WHEWELL'S THEOET OF THE TIDES. 101 



CHAPTER XII. 



THEORY OP WHEWELL OJT THE OEIGIN AISD PROPAGATION OF TIDAL WAVES, 

 — OEIGIN OF THE TIDE IN EACH OCEANIC BASIN. — "ESTABLISHMENT" OF POETS. 

 — " COTIDAL " LINES. 



The English, natural philosopher, Whewell, who during long years 

 made laborious researches on the phenomena of ebb and flow, was 

 the first to ajjply the name of " cradle of the tides " to the great con- 

 tinuous sheet of water which covers almost all the surface of the 

 southern hemisphere. It is in this vast basin, of which all the other 

 oceans are mere ramifications, that the combined attraction of the sun 

 and moon would first raise that wave, which from shore to shore dashes 

 at length against the coasts of Greenland and Scandinavia. It is there 

 that the water, a few instants after the passage of the moon over the 

 meridian, would itself attain the level of its highest elevation, and 

 would form that first regulating intumescence, which the surface of 

 all the seas would obey one after the other, as a cord shaken at one 

 of its extremities oscillates to the other end in rhythmical vibrations. 



According to this theory, the tidal wave circulates incessantly 

 throughout the Antarctic Ocean, to the south, of the extremities 

 of the three continents of Australia, Africa, and South America. It 

 follows from east to west the apparent course of the moon, and thus 

 describes a real orbit round the earth similar to that of the celestial 

 bodies. Even in the central Pacific and the Indian Ocean, the tide 

 obeys this normal impulse towards the west. It strikes the coasts 

 of Australia and New Guinea almost simultaneously ; then thirteen 

 or fourteen hours afterwards it dashes on the eastern coast of Africa, 

 from the bank of Lagullas to Cape Guardafui ; finally, seven or eight 

 hours later, the coast of South America is struck in its turn from 

 Terra del Fuego to the estuary of La Plata. 



To the north of those large oceanic tracts of the South Sea, the 

 tides, not having the same facilities for developing themselves in a 

 normal manner, would be obliged to change their direction. But in 

 spite of this deviation, they would not the less be, Whewell thinks, 



