A GREAT SEA-WAVE. 223 



form, and if the motion of this wave be watched, it is 

 seen to present the most striking contrast with the 

 turmoil and confusion at its centre. It sweeps onward 

 and outward in a regular undulation. Gradually it 

 loses its circular figure (unless the sea-bottom happens 

 to be unusually level), showing that although its 

 motion is everywhere regular, it is not everywhere 

 equally swift. A wave of this sort, though incom- 

 parably vaster, swept swiftly away on every side from 

 the scene of the great earthquake near the Peruvian 

 Andes. It has been calculated that the width of 

 this wave varied from one million to five million feet, 

 or roughly from 200 to 1,000 miles, while, when in 

 mid-Pacific, the length of the wave, measured along 

 its summit in a widely-curved path from one side to 

 another of the great ocean, cannot have been less than 

 8,000 miles. 



We cannot tell how deep-seated was the centre of 

 subterranean action ; but there can be no doubt it was 

 very deep indeed, because otherwise the shock felt in 

 towns separated from each other by hundreds of miles 

 could not have been so nearly contemporaneous. 

 Therefore the portion of the earth's crust upheaved 

 must have been enormous, for the length of the 

 region where the direct effects of the earthquake were 

 perceived is estimated by Professor von Hochstetter 

 at no less than 240 miles. The breadth of the region 

 is unknown, because the slope of the Andes on one 



