and especially in f^cotland. 285 



Thus, then, it appears that in tliose districts, both of Eng- 

 land and of Scotland, where earthquake-shocks are most fre- 

 quent, there are rents which cut through the solid ribs of the 

 earth's crust, and reach down into its unfathomable recesses ; 

 affording, therefore, a medium of communication between 

 the forces (whatever they are) which there exist, and the ex- 

 ternal agents of the atmosphere. 



It is here not undeserving of notice, that the direction in 

 which the pulsations accompanying earthquake-shocks are pro- 

 pagated, is, in most instances, coincident with the direction 

 of these fissures. Thus, on looking at the notices in the re- 

 gister of shocks in those parts of England situate to the south 

 of a line drawn between the mouths of the Severn and the 

 Thames, it will be found that, almost without exception, 

 the shocks were felt, and the undulations seen to move. East 

 and West, which is the direction of the great lines of fault.* 

 In Anglesea, North Wales, and Cheshire, where the dykes 

 and slips run NW. and SE., the vibrations are in the great 

 majority of cases stated to have been in the same direction.-f* 

 In Lincolnshire, and near the Humber, where the hills range 

 N. and S., the shocks are said to have been felt most in that 

 direction. t The shocks on 19th April 1754, 14th Septem- 

 ber 1777, and 19th November 1795, seem to have been felt 

 in a direction NE. and SW., which is parallel with the faults 

 that traverse that part of the country (between York and Man- 

 chester) most affected by them. 



One explanation of this remarkable parallelism of the direc- 

 tion of the shocks, and the line of the principal faults, is sug- 

 gested by the difficulty with which the vibrations would be 



* See, in proof of this remark, the shocks dated 25th October 1707, 8th 

 February, 9th February, 8th and 18th March 1750, 29th December 1769, 

 8th September 1773, 8th September 1775, and 23d January 1834. In refer- 

 ence to the shock of 8th March 1750 here mentioned, it may bo observed, 

 that Michell takes notice of another in London which occurred in tho pre- 

 ceding century, which ho was informed by an eye-witness moved also East 

 and West ; " being by accident in a scalemaker's shop when it happened, he 

 obsers'ed that all tho scales vibrated from cast to west" — (Phil. Tram, for 

 1760, p. 575.) 



t See, in proof of this remark, the shocks dated 2d April 1750, 18th Janu- 

 ary 1768, 28th August 1780, and 29th August 1791. 



X See notices dated 23d August 1750, and 1st August 1751. 



VOL. XXXI. NO. LXII.— OCTOBER 1841. T 



