Vol. 60.] DERBY EARTHQUAKES OF 1903. 227 



Observations nr Mines. 



As observations in mines have hitherto been few in number, I 

 endeavoured to obtain accounts from raaDy of those surrounding the 

 epicentral region. For some of the most valuable records, I am in- 

 debted to Mr. H. H. Amoid-Bemrose, F.G.S., and Mr. A. H. Stokes, 

 F.G.S., H.M. Inspector of Mines. The total number received is 

 48 from 32 mines, most of vrhich are situated between two lines 

 running east and north-east from the centre of the isoseismal 7. 



From the south-western quarter observations are entirely wanting, 

 the earthquake having passed unnoticed in the pits of Cannock Chase. 

 Towards the west, it was perceived as far as Bucknall near Stoke- 

 on-Trent (19 miles from the centre) ; towards the north-west, at 

 Monsal AVale near Buxton (13 miles, 117 yards deep) ; towards the 

 north-east, at Eckington (22 miles) ; towards the east, at Hucknall 

 Torkard (20 miles, 500 yards deep) and Bulwell (20 miles, 300 yards 

 deep) ; and towards the south at Swadlincote, near Burton-on-Trent 

 (20 miles, 470 yards deep). 



The general impression produced b}' the earthquake was that an 

 explosion or fall of rock had taken place in some distant part of the 

 mine. In the pits at Clay Cross and Morton (situated between 

 Alfreton and Chesterfield), both parts of the shock were felt, the 

 first part being the stronger and, at Clay Cross, accompanied by 

 the louder noise. In three pits, at Glapwell, Pilsley, and Swancote 

 (all in the Alfreton district), the shock was strong enough to detach 

 small pieces of shale from the roof. At Tibshelf (4 miles from 

 Alfreton), the shock caused the air in the mine to vibrate, as if from 

 an explosion. 



The sound seems to have differed slightly from that observed on 

 the surface, in being less intermittent and more monotonous, closely 

 resembling that made by a railway-train passing over iron girders 

 or a wooden bridge, and in a few cases not unlike that of an 

 explosion of firedamp or a heavy fall of rock. 



The distribution of intensity of the shock and sound presents 

 several features of interest, which seem worthy of record : — 



(1) The shock, as a rule, was not felt in the more distant mines. 

 The sound only was observed in the pits at Eckington, Teversall 

 (IS miles from the centre), Sutton-in-Ashfield (18 miles), Hucknall 

 Torkard, Ilkeston (16 miles, about 4U() yards deep), Swadlincote, 

 and Bucknall ; but in two others, Monsal Wale and Bulwell, the 

 movement was also perceived. It would seem, then, that at a dis- 

 tance the sound was a much more prominent feature than the shock ; 

 and this relative prominence was probably not accidental, for men 

 lying down to work would be in a favourable position for feeling a 

 slight tremor. Similar observations were made during the Here- 

 ford earthquake of 1896, the shock being noticed at a distance of at 

 least 20 miles, and tke sound as far as Chasetown near Walsall, 

 54 miles from the centre. 



(2) In the Great Rake lead-mine at Brassington, at a depth of 

 160 yards, and only 2 J miles from the centre, no shock was felt by 



