and espeeiallxf in Scotland, 277 



shocks, but the direction in which they acted on bodies, means 

 would be obtained of determining the point in the earth's in- 

 terior from which the shocks originated. 



Whilst thus it seems impossible to deny that vibrations 

 transmitted from below are capable of producing undulations 

 on the surface of the ground, and that vibrations actually ac- 

 company these undulations, there is a circumstance which 

 seems not easily explicable on any other supposition than that 

 the undulations are caused by such vibrations. It has just 

 been shewn, that the undulations are always strongest on allu- 

 vial plains. But if the undulations were caused by a corres- 

 ponding movement in a liquid nucleus below the crust of the 

 earth, there should be scarcely any appreciable difference on 

 this account. The whole mass would be very nearly equally 

 affected ; and if there were any difference in the effect of the 

 supposed subterranean undulations, they would be less visible 

 on alluvial districts. But on the theory of vibrations, it can 

 at once be understood why those parts which are soft and 

 yielding should, consistently with the fact, be the most affected. 

 3. Bents and subsidences produced by Earthquakes. — These 

 effects have fortunately been exhibited in this country on a 

 very small scale. The earthquake of November 1755, for 

 example, which produced great rents on the coast of Por- 

 tugal, caused a new quay at Lisbon to be submerged to an 

 unfathomable depth, and made an opening in the earth near 

 Morocco which swallowed up a village with eight to ten thou- 

 sand inhabitants, scarcely produced any derangement of the 

 earth's crust in Great Britain. The hot springs at Bristol 

 were discoloured, and for some months rendered unfit for use ; 

 the rocks in Derbyshire mines were heard to grind on one 

 another ; a rent of 150 yards in length, about one foot deep 

 and six inches across, was formed at these mines ; — but no 

 very material derangement of the earth's interior under this 

 country, seems to have been caused. 



On glancing over the register, however, some remarkable 

 cases of fractures on other occasions will be perceived. A 

 hole in the ground, sixty or seventy yards in diameter, was 

 formed at Whitehaven during the cartli quake of February 

 1792, — whether above any excavations for coal is not stated. 



