316 Dr. C. Davison—British Earthquakes. 
The number of records of the time is 67. Of these 20 are regarded 
as accurate to the nearest minute, and 17 of them agree in indicating 
6.15 a.m. as the correct time. 
Notwithstanding the large number of records, for which I am chiefly 
indebted to the kindness of Mr. G. 8. Rae of Kilcreggan and 
Mr. John Robertson, F.R.G.S., of Strachur, the places at which the 
earthquake was observed are few in number. It is thus impossible 
to determine the boundary of the disturbed area with any approach 
to accuracy. Roughly it is an oval curve, 25 miles long, 21 miles 
wide, and containing about 400 square miles, with its centre 11 miles 
north of Dunoon and its longer axis directed about N. 41° E. 
At most places the shock consisted of a single series of tremors, 
its average duration being four seconds. At Strachur, however, two 
parts were felt by four out of eighteen observers, the average interval 
between them being three seconds, the first part in each case being 
regarded as the stronger. 
The sound was heard by all the observers. In 27 per cent. of the 
records it was compared to passing wagons, etc., in 29 per cent. to 
thunder, in 14 to wind, in 15 to loads of stones falling, in 4 to the 
fall of a heavy body, in 10 to explosions, and in 1 per cent. to 
miscellaneous sounds. The beginning of the sound preceded that 
of the shock in 24 per cent. of the records, coincided with it in 72, 
and followed it in 4 per cent.; the end of the sound preceded that of 
the shock in 23 per cent. of the records, coincided with it in 67, and 
followed it in 10 per cent.; the duration of the sound was greater 
than that of the shock in 18 per cent. of the records, equal to it in 
74, and less than it in 8 per cent. 
About four years before, on September 18, 1904, a somewhat 
stronger earthquake (of intensity 5) was felt in nearly the same 
district. This earthquake disturbed an area of about 564 square 
miles, the centre of the isoseismal 5 being 9 miles west of Dunoon 
and lying on the longer axis of the area disturbed by the earthquake 
of 1908, and at a distance of about 14 miles in a south-westerly 
direction from its centre.t It is thus very probable that the two 
earthquakes are connected with the same parent fault, and that the 
movement along this fault in 1904, while relieving the stress in 
the portion west of Dunoon, increased the stress in the neighbouring 
portion of the fault, and thus prepared the way for the movement 
four years later in the district to the north of Dunoon. 
9-14. Ochil Earthquakes: July 17 — October 20, 1908. 
9. July 17, 1908: 5.27 p.m.—A slight but distinct tremor, felt at 
Alva and Menstrie, and accompanied by noise. Another, but still 
slighter, shock is said to have been felt at Menstrie after 9 p.m. on 
the same day; but, as I have no direct evidence from that place, it 
should be regarded as of doubtful seismic origin. 
10. September 2, 1908: 8.16 a.m.—A single shock, of intensity 3, 
felt at Menstrie, and accompanied by a rumbling noise. 
11. September 2, 1908 : 8.51 a.m.—A single shock, of intensity 3, 
felt at Menstrie, and accompanied by a rumbling noise. 
1 Grou. Mac., 1908, Vol. V, pp. 297-8. 
