C. Davison — British Earthquakes of 1889. 371 



Mrs. L. Davy (Tresmere), Miss F. E. Jenkin (Liskeavd), Mr. W. E. 

 Parsons (St. Breward), and Miss L. Thome (Liskeard). 



Doubtful Earthquakes. 



1. Invergarry, June 19, 1889, 7h. 4:0ra. (see p. 365). 



2. Little Rhondda Valley (South Wales), June 22, 1889, about 

 22h. 30m. ; intensity, V. 



A shock, supposed to be that of an earthquake, was felt at this 

 date in and near the Little Ehondda Valley. The area disturbed by 

 it was very small, probably not more than a few miles in its greatest 

 diameter*. It was felt at Llwynypia, Pontygwaith, Tylorstown, 

 Watts Town, Ynishir and Ystrad. 



The disturbance, which lasted a second or two, consisted of one 

 vibration, and at Ynishir is described as having been like the shock 

 of a blasting explosion, but much stronger. It was accompanied 

 by a deep rumbling noise, like distant thunder, at Llwynypia, 

 Pontygwaith, and Watts Town. The intensity was IV. at Ponty- 

 gwaith, but cannot have been less than V. at Llwynypia and 

 Ynishir. The shock was felt by workmen underground in the 

 Ynishir Steam Colliery, and in one or two other collieries in the 

 adjoining district. 



This is all the evidence I have been able to obtain, and I do not 

 think it is sufficient to put beyond doubt the seismic origin of the 

 shock. For so small a disturbed area, the intensity is unusually 

 great, arguing a very small depth for the centre of disturbance ; and, 

 besides this, the mining operations of the district are being carried 

 on so rapidly and extensively that, from time to time, considerable 

 masses subside, occasionally, it is said, causing tremors very like 

 those of an earthquake. 



Authorities.— '''Naime," vol. 40, p. 208; "South Wales Daily 

 News" (Cardiff), June 24, 1889. For other information contained 

 in the above account, I beg to thank Mr. W. Galloway, Mr. J. J. 

 Thomas, of Ynishir, and Mr. E. R. Hood, of Gilfaoh. 



3. Lyme Regis, July 5, 1889, between 23h. and 23h. 15m. 



Noises were heard at intervals between the times stated. They 

 " consisted of a distant rumble which grew nearer till at last the 

 windows of the houses rattled and in some cases distinct vibrations 

 of the houses were felt." They were probably not caused by the 

 firing of guns at sea : and they may have been due to earthquakes, 

 though the evidence is clearly incomplete. 



This note is taken from a letter by Mr. A. R. Sharpe, in Nature, 

 vol. 40, p. 294. 



Conclusion. 



With one possible exception (that of Ben Nevis), the earthquakes 

 of 1889 are typical examples of British shocks — they occurred in 

 districts where earthquakes are rarely felt, and their disturbed areas 

 are circular or only slightly elliptical in form. Turning to a more 

 distinctly seismic area, Switzerland for example, we find that the 

 disturbed areas are often extremely elongated, the longer axes 

 being parallel to those of the neighbouring Alpine chain; earth- 



