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XXXVI. A Table of Shocks of Earthquake, from September 

 1S39 to the end of 1841, observed at Comrie, near Crieff. 

 By James Drummond, of Comrie*. 



CONSIDERING that the theory of the Comvie earth- 

 quakes has not yet been satisfactorily established, I thought 

 that an account, by a resident on the spot, of the shocks du- 

 ring the last two years might be of interest, and perhaps of 

 value, to the readers of the Philosophical Magazine, and to 

 those engaged in inquiring info these pha^nomena. It is not 

 my intention to enter into any discussion on the question just 

 now, but I think it right to say that these observations origi- 

 nated in the dissatisfaction I feel as to the theories heretofore 

 propounded, and as to the seat of the disturbance. When I 

 consider that the shocks are only of modern occurrence, that 

 they date only from the opening of quarries into the basaltic 

 dykes on each side of the river Lednoch, and that they are 

 consequent on floods of that river, I cannot feel justified in 

 giving my assent to the doctrine, that they are derived from 

 the percolation of water. Neither can I admit, as,is the po- 

 pular belief here, that the seat of the disturbance is in any of 

 the neighbouring mountains. 



I flatter myself, also, that a register of shocks from a resi- 

 dent at Comrie will not be without its uses, as fiom greater 

 habitude the people of this place are better able to distin- 

 guish the shocks. 



Before coming to the register, 1 think it advisable to make a 

 few preliminary observations as to some of the circumstances 

 attendant on the shocks. With regard to 1839, in which the 

 disturbances were most frequent, both the harvest and winter 

 were, with the exception of very short periods, wet. About 

 eleven on the morning of the 20th of October a drizzling rain 

 came on and continued until seven in the evening of the 23rd, 

 when it cleared up and the stars appeared ; neither the sun, 

 moon, nor stars having been seen for about fifty-six hours ; at 

 half-past seven, however, it began to rain heavily, and when the 

 shock took place the rain increased. I do not remember that 

 there was any strong wind at the time. On the morning of 

 the 24th it was fair again. It is to be remarked that the rain 

 was general, and the shock was felt over all the central parts 

 of Scotland. It has been said that this shock was felt in all 

 parts at one and the same instant, but I beg leave to demur 

 to the possibility of this, as at Inverness, for instance, the 

 sound was heard some time before the shock, showing that 

 the sound had travelled faster. 



* Communicated by the Author. 



