KANGRA KULU EPICENTRAL AREA. 35 



Using West's simplified formula for determining the acceleration of 

 the wave particle, a formula wnicu has stood the test of much experi- 

 mental proof, we have : — 



1 x 



where x *s half diameter of the base and y = the height of the centre 

 of gravity. 



Then, in the three cases above, we have as follows : — 



For (A) / = greater than 11§ ft. per sec. per sec. 

 .For (B)/=* about 13 ,. „ 



For (C)/'= less than 19 „ 



Since in the case of (A) both bodies were upset towards the direc- 

 tion of shock, and in the case of (B) one towards and one away from 

 that direction, whilst in the ease of (C) they were not upset at all, we 

 may deduce a rate certainly between ] If and 19, and probably near 

 13 ft. per sec. per sec. for the acceleration of the wave particle at 

 Kaugra. 



But according to Prof. Omori, the formula : — 



where 2c is the double amplitude or range of motion of the overturn- 

 ing edge, will yield a limiting value for the amplitude oJ the earth 

 vibrations in the case of short periods where the pillar is over- 

 turned towards the direction of impulse. Using it we obtain the 

 result, 



a = 9 J inches, 



an amplitude which is large, but not excessive in the case of soft 

 ground near the epicentre of a great earthquake. 



1 Seismological Journ. of Japan, Vol. XVIII, p. 120 (1893). 



d2 



