44 STUART : THEl SRIMANGAL EARTHQUAKE OF 8TH JULY 1918. 
His method is as follows : — 
West Bromwich to Riverview ...... 163* 4' 
West Bromwich S— P 554 seconds 70° 8' 
This difference of 10 seconds must be divided between the two stations, viz., 
5 seconds each, i.e., the tabulated time is 5 seconds too great. Professor Turner's 
investigation suggested a correction of 6 for 73° 8', agreeing very well with the 
present example." 
The time of occurrence at origin as deduced from British records 
is therefore 10 hours 22 minutes 2 seconds. Turning now to the 
Indian observatories, one finds that the best seismograms are those 
recorded at Bombay. Both the Kodaikanal and Colombo records 
are unusual, and are much obscured by that of the local sympathetic 
shock the existence of which was deduced in my preliminary report. 
This sympathetic shock will be discussed in a subsequent chapter. 
For the present the beginning of the Colombo and Kodaikanal 
records will be taken to represent approximately the arrival of the 
Preliminary tremors from the Srimangal centrum, and the maximum 
at Kodaikanal, and the first maximum at Colombo, both of which 
are such marked features on the records, to represent the arrival of 
the long waves from the Srimangal centrum, — an assumption which, 
it will be seen, makes the two records agree remarkably closely 
with the records of other observatories. 
The arrival of the Preliminary tremors at Bombay at 10 hours 
26 minutes 12 seconds gives a calculated time of origin at the earth- 
quake centre of 10 hours 21 minutes .50 seconds, and, adopting this 
provisionally, the differences between the observed and the calcu- 
lated tunes of arrival of P at other stations are shown in the follow- 
ing table (on next page). 
The times of arrival of P at Dehra Dun and Colombo would 
appear to be incorrect. The Colombo time certainly is, as Mr. 
Evans, when sending me the copy of the seismogram Stated " there 
has been the inevitable loss of fine detail in reproduction, but there 
is a slight thickening of the line slightly previous to its displacement 
towards the v)est by the large waves." 
As one millimetre of record represents slightly more than one 
minute of time in the case of the Colombo Mihie seismograph, 
the slight thickening of the Hne (representing the arrival of P from 
therefore to Riverview should be 153° 4' — 70" 8' 
= 82" 6' 
10 seconds. 
