TIME OF K.\I!Tn(,)l'AKE, RATE OV PROPAOATTON. 
37 
Colombo Observatory. 
The instrument here is of the Mihie type with horizontal pen- 
duhini which is set N-S. Its period is about 17 seconds, and its 
sensitivity is 0405 for 1 mm. of trace. The time of commencement 
of the shock is 15 hours 57 minutes 30 seconds Standard Mean 
Time (10 hours 27'5 minutes Greenwich Mean Time) : Maxima 
16 hours 2 minutes and 16 hours 13 minutes Standard Mean Time : 
ending about 18 hours 16 minutes Standard Mean Time: iiiiiplitude 
17 mm. 
Plate 7, shows a reproduction of the Colombo seismogram. 
A check mark had been made by obscuring the light by hand 
commencing at 16 hours 23 minutes Standard Mean Time. The 
Director of the Observatory informs me that there has been the 
inevitable loss of fine detail in reproduction, and that there is a 
slight thickening of the line slightly previous to its displacement 
towards the west by the large waves. 
Madras Observatory. 
This observatory has not an earthquake-recording instrument, 
but there is evidence to show that the observatory clocks were 
affected by the shock, and as the earthquake occurred while the 
daily time signal was being sent out from the observatory there is 
an exact record of when this disturbance occurred. I have already 
quoted {sufra, p. 32) the report furnished by the Calcutta Obser- 
vatory to the press, shortly after the earthquake, and this contains 
details of the effect of the earthquake on the Observatory clocks. 
Plate 5 shows a reproduction of the time signal that was being 
recorded in Calcutta when the earthquake occurred. The solid line 
represents the record of the Calcutta clock while the broken line 
immediately below it represents the time signal from Madras, both 
being recorded electrically. It will be seen how irregularly the 
pendulum of the Calcutta clock was moving, but the great interest 
of the record lies in the fact that the Madras record also becomes 
irregular at about 15 hours 57 minutes 58 seconds and continues 
so for twelve or thirteen seconds, the maximum disturbance being 
apparently at about 15 hours 58 minutes 7 seconds. Star obser- 
vations taken in Madras on 9th July showed that something very 
unusual had happened to the Madras sidereal clock and there seems 
