186 EARTHQUAKES. 



almost 6,634 miles .... 15,000 feet deep 



and 60 „ . . . . 12,000 



By Scott-RusselFs rule, or, what is almost identically 

 the same, by Airy's general formula, we can calculate 

 how long it would take such waves as we have been 

 speaking about to travel over the different portions of 

 each of these lines, and by adding these times together 

 we obtain the time taken to travel across any one line. 

 I have made these calculations, but as I get in every 

 case answers which are too small, I think it unnecessary 

 to give them. 



The actual times taken to travel the distances just 

 referred to were. 



To Japan (Kameishi) . , . . 23 hr. 38 min. 



„ New Zealand (Wellington) . . . 18 „ 23 „ 



„ Samoa 14 „ 58 „ 



„ Sandwich Islands (Honolulu) . . 14 „ 53 „ 



From San Francisco to Simoda the line is almost 

 3,567 miles, 3,000 fathoms deep, 840 miles, 2,500 fa- 

 thoms deep, and 120 miles 1,000 fathoms deep. This 

 gives an average depth of about 2,854 fathoms. Bache 

 calculated the depth at 2,500 fathoms. 



If we are to consider that, because the sea wave at 

 Simoda came in some time after the land shock had 

 been felt, the origin of this earthquake, instead of being 

 at Simoda, was some distance out at sea, this calculated 

 depth would be reduced. 



