82 THE BOTTOM OF THE SEA. 



of Chili ; only in this case the soil remained elevated 

 some five or six feet above its former position. After 

 the earthquake which destroyed Old Callao, on the 

 contrary, the soil was found to be permanently 

 lowered some four or five feet. The effect of the 

 raz de maree was similar to the preceding. 



It is obvious that earthquakes which extend under 

 the ocean must stir the waters to their most profound 

 depths. They give rise to a phenomenon which has 

 been named by Mr. Scott Russell the " Wave of 

 Translation." He has demonstrated that the move- 

 ment of the water is as great at the bottom of the 

 sea as at its surface — a fact that has been verified by 

 the transport of objects that were lying at the bot- 

 tom. Further, the wave advances by forming a 

 swelling on the surface without breaking like other 

 waves, and its speed of propagation is proportional to 

 the square root of the depth. If its course be ob- 

 structed by an abrupt elevation of the sea-bottom, 

 its effects will be exaggerated and complicated with 

 those of the ground-swell. As it reaches the shore it 

 produces the raz de maree. 



Lisbon was destroyed on the 1st of November, 

 1755, by the most violent and most extended earth- 

 quake on record. The shock was felt on the same 

 day over the North Atlantic Ocean ; between Spain, 

 the Antilles, and Newfoundland ; in Canada • in Great 



