308 Dr. C. Davison — British EartZ/qualies. 



remaining cases generally to thunder. The beginning of the sound 

 coincided in every case with that of the shock, while the end of the 

 sound and shock were also as a rule simultaneous. 



The earth-shake was obsein-ed in pits at Llwynypia, Wattstown, 

 Gelli, and Ynyshir ; in the two first at a depth of 500 yards. Gelli is 

 close to the boundary of the disturbed area, and Ynyshir about half 

 a mile distant, so that the disturbed areas on the surface and in pits 

 were roughly coincident. At Llwynypia the sound was described as 

 a terrific crash, followed by low, deep rumbling. 



The centre of the disturbed area lies close to the termination (as 

 mapped) of the Cymmer fault, and on its downthrow side. The earth- 

 shake was thus in all probability due to a slip of this fault, brought 

 about by the withdrawal of coal, etc., from the mine below. 



Doubtful Earthquakes, 



Church Stretton : October 22nd, 1904. — Time of occurrence, about 

 10.50 p.m.; intensity, 4; number of records 13, from 5 places, and 

 negative records from 5 places. 



The five places at which the shock was felt (Church Stretton, Shelve, 

 Stapleton, Stiperstones, and Woolstaston) lie within an oval curve, 

 IQ^ miles long from north-east to south-west, 8-i- miles wide, and 

 containing about 70 sqiiare miles. The centre of the area is about 

 10 miles south-west of Shrewsbury. The shock was brief and slight, 

 and was accompanied by a loud noise, which was compared to the roar 

 of a train passing close at hand, the fall of a heavy body, or an under- 

 ground explosion. 



Molyhead : June 26th, 1907. — At 9.5 a.m. a shock of intensity 4, 

 consisting of a single series of vibrations, was felt at Holyhead. It 

 was preceded by a sound like the passing of a heavy vehicle. 



RePOETED EAKTHaUAKES. 



A large number of disturbances, supposed to be those of earthquakes, 

 have been reported during the years 1904-1907. In the present 

 section are included only those of which accounts haA'e been inserted 

 in newspapers. If they are not all due to artificial disturbances, the 

 evidence seems to me insufiicient to entitle them to the rank of doubtful 

 earthquakes. 



Napton f Warwickshire J : January 26th, 1904. — At 12.4 a.m. a slight 

 shock was felt, followed by tremors that were distinctly perceptible for 

 15 to 20 seconds. Inquiries made in the local newspapers elicited no 

 further accounts. 



Aherystwith : July \Zth, 1904. — At 8.10 a.m. a rumbling sound 

 was heard, and at 10.28 a.m. a rather strong shock, accompanied by 

 a loud rumbling sound, was felt. Inquiries made in the district 

 around Aherystwith show that the disturbances were confined, or 

 practically confined, to that town. 



Newlury: Noremher 2bth, 1904. — Shortly before noon, and again after 

 3 p.m., dull reports, accompanied by the shaking of windows, were 

 heard near the borders of Hampshire and Berkshire, to the east of 

 Salisbury Plain. The area from which I have received records is 

 24 miles long from east to west, 22 miles wide, and contains about 



