1897-98.] Note on Indian Earthquake , 12 th June 1897 . 19 
not have been instantaneous, but must have acted for some consider- 
able time; for vibration of the above amplitude, if caused by, 
say, momentary action of a deflector, would die out within half a 
minute, while the movements shown in the trace lasted for over 
three minutes. The first wave appears to have commenced the 
disturbance at 6'' 5, attained the maximum at about 8', and ended 
at about 10' past four. The second commenced immediately after 
this, reached its maximum effect at about 12', and ended at 14' 
past four. 
mil 
ft illlii 
MM 
Fig. 3. 
The Observatory has two vertical force magnetographs, both of 
which show the two waves clearly. The maximum effect of the 
first disturbance coincides in time with the greatest disturbance in 
the declination magnetograph. The amplitudes of the vibrations 
above the curve are somewhat smaller than those below the curve 
(this is more clearly shown in vertical force No. 2), which shows a 
slight decrease in vertical force during the time of disturbance. It 
may be noted that the time of vibration of this magnet is 5*35 
seconds — about the same as that of declination magnet. 
