138 Mr D. Milne on Earthquake-Shocks felt in Great Britain^ 



on 23d October 1839, and some of the most striking circum- 

 stances which accompanied it, we shall now shortly notice the 

 results which seem deducible from these details ; and then pro- 

 ceed in noticing the shocks which subsequently occurred. 



1. The shock in question was felt throughout two- thirds of 

 Scotland. The southern limit of the region affected, was 

 nearly coincident with a line drawn from the Solway to the 

 mouth of the Tweed. Its northern limit was as nearly coin- 

 cident with what is known as the Great Glen of Scotland, viz. 

 along the course of the Caledonian Canal. The shock was 

 felt on the east and west coasts, at places comprehended be- 

 tween the southern and northern limits above described. 



2. Throughout the whole of the region so affected, the 

 shock appears to have been felt simultaneouslt/, or at least so 

 nearly so, that it is impossible to discover any appreciable in- 

 terval between the observations of the shock in different 

 places. 



Little dependence, however, can be placed upon this infer- 

 ence, in consequence of the impossibility of trusting to the or- 

 dinary clocks and watches, by which the observations were 

 made. 



3. The shock was not felt everywhere, with the same degree 

 of intensity. It was greatly more severe in Comrie, and the 

 immediate neighbourhood of that village, than in any other 

 part of Scotland, — the extent to which walls were rent or 

 thrown down, and the loudness of the attendant noise, being 

 incomparably greater there than any where else. 



The intensity of the shocks, at other places, was not in pro- 

 portion to their distance from Comrie. Thus, in Aberdeen- 

 shire, at places exceeding 100 miles from Comrie, the shock 

 exhibited much more violence than in the Lothians, though 

 only half as distant. The lines of equal intensity appear to 

 have formed ellipses, of which Comrie is the centre, and of 

 which the longer diameter is about NE. and SW., or parallel 

 with the chain of the Grampians. This circumstance may 

 probably be accounted for, by the geological structure of this 

 part of the island. If the shocks were caused by vibrations 

 transmitted through the earth's crust, they would be trans- 



