Dr. C. Davison— British Earthquakes, 1900. 361 



souulI, 9 per cent, compare it to passing waggons, 27 per cent, to 

 tluindei", i) per cent to wind, 36 per cent, to a cart of coals or bricks 

 being emptied, 9 per cent, to the fall of a heavy body, and 9 per 

 cent, to the distant fii'ing of cannon. Thus, the reference to sounds 

 of brief duration is even more marked than in the earlier shock. 

 The beginning of the sound preceded that of the shock in 2 cases 

 and coincided with it in 5 ; while the end of the sound coincided 

 with that of the shock in 4 cases. 



Origin of the JSarthqnalces. — From the seismic evidence, we can 

 determine only the direction of the originating fault, which must be 

 about E. 13° N. and W. 13° S. If it hades to the north, the 

 fault-line must lie to the south of the centres of the disturbed 

 areas, and if to the south on the north side. 



On the map of the earthquakes is shown that part of the great 

 Ochil fault which traverses tlie disturbed areas of the earthquakes. 

 Its general direction is E. 11° N. and W. 11° S., and, if the fault 

 haded to the north, it would thus satisfy the seismic conditions ; but 

 this, I am informed through the kindness of Sir A. Geikie, is not the 

 case. " It is known to hade to the south both by direct observation 

 and by the effects of denudation upon the intrusive sill of dolerite 

 in the Carboniferous rocks, where it is thrown against the andesites 

 and agglomerates of Lower Old Red age." As the shock would be 

 less strongly felt on the hard compact rocks of the Ocliil Hills than 

 on the softer rocks to the south, it follows that the earthquakes 

 cannot be attributed to slips along the Ochil fault. 



There is no other parallel fault of any consequence marked on the 

 Survey map (Sheet 39), though several faults cross the Ochil Hills 

 in a nearly perpendicular direction. The only conclusion we can 

 come to, therefore, is that the earthquakes are connected with some 

 fault or faults, whose existence has not yet been ascertained by 

 geological evidence. 



Doubtful Earthquake. 



Pendleton {near Manchester), April 7, 1900. — An earth-shake, 

 somewhat similar to that of Feb. 27, 1899, occurred at 1.17 a.m. on 

 April 7. Mr. Mark Stirrup has again kindly sent me records of this 

 shock, from which it appears that the disturbed area, as before, is not 

 more than 4 or 5 miles in diameter, and that the centre is close 

 to the Irwell Valley fault, but a rnile or two further to the south 

 or south-south-east of that shaken in 1899. At Pendleton the 

 vibration resembled that felt in a house when a heavy traction- 

 engine passes ; and the sound appeared as though the mortar and 

 walls were being crushed. In the collieries, at a depth of about 

 3,000 feet, the noise was also considerable ; and the shock is said 

 to have caused dust to rise. As the intensity of the shock was 

 4 or 5, and the disturbed area very small, the depth of the centre of 

 disturbance must have been slight. The evidence is less complete 

 than in the former case, but, so far as it goes, it supports the view 

 of the origin of these earth-shakes in mining districts which 

 I suggested in my last paper on British earthquakes. 



