56 Earthquake at the Philippine Islands. 
that the oscillation from E. to W., true, had an amplitude of 
10°—5° to the E. and 5° to the W., but that in the direction 
from N.E. to 8. W. the aapitade was 17° , 9° to the S.W. and 
8° tothe N.E. aa’,bb’, cc’ are directions of the first, second 
and third — Robe eae In the vertical seismomenter the 
index moved 2 
Vibrations sued yet there was a marked diminution in 
frequency and intensity. The pendulum, which had not been 
quiet since the 18th until 3 Pp. M. of the 21st, ewe motionless 
for long intervals in the three following days. On the 25th, at 
4 2’ a. M., another shock was felt; it was of feeble ed 
yet of interest since the record bears evidence as to the gradual 
change in the center of seismic radiation which had been in 
ee The direction of the undulation (fig. 5) was N. 64° E. 
oS. 64° W.; the amplitude of the oscillation was only 8° 54’. 
No vertical movement was appreciable, the vertical seismometer 
indicating a change of only 0-7™™ from the normal position. 
After this exposition of the results, we will recapitulate 
briefly the points established by the tracings on the lycopo- 
ium powder as shown in the figures 
(1.) In the registration of the 14th (as represented in fig. 1), 
two radial centers are shown ; the first in the second quadrant, 
from the point at which the movement began, and the second 
in the first quadrant where it ended.—(2.) In that of the 18th, 
also, we find the same two centers, but, besides these, other new 
ones, the pendulum moving in all imaginable directions. (See 
fig. 2.)\—(3.) In that of 3 P. M. of the 20th (fig. 3), the focus 
of the second quadrant worked with wonderful violence, and 
the others had disappeared.—(4.) In that of 10" 40’ p. m. of 
the 20th (see fig. 4), a very great variation in the seismic foci 
is shown: the oscillations from E. to W., which correspond to 
the foci that before operated with so great violence, were gradual 
and of much less intensity, while, on the contrary, those from 
N.E. to 8. W. indicate powerful undulations between these points. 
—(6.) Finally, in that representing the last oscillation on the 
morning of the 25th (see fig. 5), there is manifested only the 
one seismic focus of the first quadrant, and this of slight in- 
tensity, the others having wholly disappeared. In each of the 
figures the small circular dot one side of the center shows the 
position of the ring given by the first impulse. 
We will not now offer any deductions from the facts ob- 
served, desiring only to place them before those versed in these 
subjects that they may themselves study them without preju- 
dice from our opinions. 
ore 1.—It should be understood that when we speak of the 
moyement of the pendulum from one side to the other of the 
