88 REPORTS ON THE STATE OF SCIENCE.—1912. 
Seismic Activity—continued. 
Time at wg ae Lat. and Long. Remarks 
Date No. Origin District of Origin & F=Felt ; D=Destructive 
1909 h. m. 
Dec. 9 | 2162 | 21.42 F, 127 E. 28. | Ambon and Piroe, F. 
9 | 2163 | 23.27 E,, M, 147 EK. 14.N. 
‘ 9 | 2163 | 23.27 M, 176 E. 0 N.S. | Determined from 
Samoa, Honolulu 
and Sydney. 
» 22 | 2180 | 12.38ca F, 152 E. 3 8. 
» 23 | 2182 | 22.1343 F, 160 E. 9S. 
» 28 | 2187 19.17-+2 F, 129 E. 58. 
III. Relation of Amplitude in Seconds of Arc to the Distance 
of an Origin. 
Those who have experienced earthquake movement in the vicinity 
of an epicentre have many reasons to conclude that it is undulatory 
in character. Earthquake earth-waves have frequently been seen. 
Water in tanks, ponds, and in small vessels has been observed to flow 
irregularly and intermittently first in one direction and then in another. 
The movement of the fluid suggests that the containing vessel has been 
subjected to a series of tilts. Pictures and objects free to swing do so 
in an extremely irregular manner. They may moye, say, to the right, 
stop, go further to the right, and again come to rest, after which they 
may swing suddenly in an opposite direction. The hanging lamp or 
whatever the object may be does not swing freely like a pendulum, 
but follows a series of irregular displacements of the supporting point. 
At considerable distances from an origin where the movements are less 
violent, although they are not so irregular in character, the records from 
seismographs also give evidence of angular displacements. Two similar 
horizontal pendulums similarly oriented, but adjusted to have different 
periods, give for the large waves of crypto or teleseismic disturbances 
records of amplitude the linear measurements of which are very 
different. The instrument with the longer period yields the larger 
diagram. If, however, we convert these displacements into angular 
measure we find that the two records are comparable. 2 
In the British Association Report for 1893, p. 221, I gave angular 
measurements for earth-waves which form portions of earthquakes 
which could be felt. I obtained these records from an ‘ angle measurer 
or clinometer.” A similar but much more sensitive apparatus was in 
1903 devised by Dr. Schliitter. The object was to measure the angular 
component of teleseismic motion. This does not appear to have been 
detected. 
This means that the conclusions arrived at by Dr. Schliitter, which 
at the present time are shared by several seismologists, are very 
different from mine. 
Following my own ideas, in the accompanying diagram I have 
given curves which show for six large earthquakes the approximate 
relation between the amplitudes of teleseismic disturbances in angular 
measure and the distance from an origin measured in geographical 
