370 C. Davison — British Earthquakes of 1889. 



Sound-Phenomena. — The sounds accompanying the earthquake 

 have been already alluded to : they form perhaps its most note- 

 worthy features. They seem to have been of the usual description, 

 being compared to thunder, to heavy waggons passing rapidly along 

 adjoining roads, and to the roaring of a chimney on fire. At the 

 following places the sound is said to have accompanied the shock : 

 Camelford, St. Breward, St. Clether, Temple and Trenegloss. It 

 preceded the shock at North. Petherwin, and perhaps also at North 

 Hill and Tresraere. At Warleggan, the rumbling sound was beard 

 just after the shock, " as if a waggon had run away down the bill 

 outside our house : it increased in sound and then appeared to me 



like an express train going through a station The rumbling 



ended quite abruptly." At Liskeard, it preceded the shock ; but 

 another correspondent at the same place informs me that it was 

 heard both before and after the shock, both times very low, but 

 rather louder after than before. 



The earthquake-sounds were heard at all places from which I 

 have detailed accounts. The sound area and the disturbed area may 

 therefore have been coextensive, or nearly so. Further, since the 

 sounds were the most notable part of the phenomenon near the 

 epicentrum, and at a place like Liskeard near the boundary of the 

 disturbed area were only heard by a few persons, we may conclude 

 that the intensity of the sound diminished more rapidly than that of 

 the shock as the distance from the epicentrum increases ; and, con- 

 sequently, that the sound-focus was nearer to the surface than the 

 rest of the seismic focus. 



Position of the Epicentrum and Geological Belations. — The epicen- 

 trum of the earthquake is about 2f miles S.W. of Altarnon, i.e. not 

 far from the centre of the great granite boss which occupies so large 

 a part of East Cornwall. It is also noteworthy that the duration of 

 the shock was in some parts considerable, as much as 10 or 12 seconds, 

 arguing probably a larger seismic focus than in any of the previous 

 cases ; further, that the longer axis of the disturbed area runs east 

 and west, i.e. parallel to the direction of folding of the district. 

 Though we may not at present be in a position to assign a definite 

 origin to this earthquake, it seems at least probable that it had 

 some connexion with the geological structure of the district, and 

 that the forces which have combined in producing that structure 

 have not yet ceased to act. 



Authorities.—" St. Austell Weekly News," Oct. 12 ; "West Briton 

 and Cornwall Advertiser" (Truro), Oct. 10; "Western Morning 

 News" (Plymouth), Oct. 8. 



The earthquake was but slightly noticed in the local press, and 

 nearly all that is of value in the preceding account I owe to the 

 kindness of the following ladies and gentlemen : the Eevs. R. H. 

 Boles (St. Breward), C. Bridgewater (St. Tudy), J. E. Browne 

 (Bodmin and Temple), W. Jago (Bodmin), A. H. Malan (Altarnon), 

 C. Olive (Warleggan), J. Partridge (St. Clether), T. B. Trentham 

 (North Petherwin), Canon Vautier (St. Mabyn), T. Walters (Boyton), 

 and T. Willing (North Hill); Mr. J. C. Chapman (Trenegloss), 



