1872.] 



OLDHAM AND MAHET CACHAE EAETHQTJAKE. 



267 



And where apertures are provided (at the same moment almost) 

 by the earth-fissures, the rising liquids will, through these, find 

 easy vent. 



As respects the height in the fissures //' to which the water of 

 the water-bearing or ooze-bed o o can rise when the mass C is 



Fig. 5. — Diagram iUustrathig the Rise of Water in tJie Fissures. 



pressed down upon it by the vertical component of the wave-motion, 

 if V = the maximum velocity of the wave-particle, which is in the 

 contrary direction, impressed upon the mass C, Avhose weight is = 

 W, then the impressed work accumulated in C is 



TJ — 1 _ V2 • 



'7 , 



and as the mass C is not free to move in the direction B A, the 

 horizontal component of the wave's motion, whose wave-path is 

 A B, makes the angle B with the horizon ; i. e. 6 is its " angle of 

 emergence." 



Then, in the vertical, the impressed work is 



but 





V2 



(V sm df = 2g h, or h = i—, 



h being the height due to the velocity in the vertical. 



Hence the minimum height to which the water from the ooze- 

 bed will be raised by the depression of the mass C is =: 7i in feet, 

 provided there is enough water in the ooze-bed, and that the latter 

 is easily compressible. 



This is on the assumption that the specific gravity of the mass C 

 is the same as that of water ; but as dense earth is about sp. gr. 1-92, 

 so the actual minimum height of water-rise in the fissure /' will be 



1-92 7i. 



We have no information as to either the wave-velocity or the angle 

 of emergence for any locality in this Cachar earthquake. If, how- 

 ever, we assume the velocity in the vertical component to be 30 feet 



v2 



