244 



THE GEOLOGIST. 



The instruments employed to indicate the shocks were 

 those described last year. The new instruments pro- 

 vided by the Committee have not with one exception, 

 yet been affected, having been but a short time at their 

 respective stations; and out of the sixty shocks above 

 mentioned, there were but three occasions on which these 

 instruments were moved. 



1. On the 26th July, 1841, the inverted pendulum set in 

 the steeple of Comrie parish church, was thrown about half 

 an inch to the west, apparently indicating a horizontal 

 movement of the ground eastward, to the same amount. 

 An upward heave of the ground, to the extent of half an 

 inch, was also indicated by two instruments, one of them 

 being a horizontal bar, described in the course of the 

 Report. 



2. The next shock by which the instruments were affected 

 occurred on the 30th July, 1841. The inverted pendulum 

 in Mr. Macfarlane's house at Comrie, vibrated to the extent 

 of half an inch, in a direction south and north ; whilst at 

 Tomperran (about \\ mile east of Comrie), an instrument 

 on the principle of the common pendulum vibrated east and 

 west. The instruments for showing vertical movements 

 were but slightly affected. Mr. Macfarlane describes this 

 shock as very severe, though not so violent as that of Octo- 

 ber, 1839 : estimating the former at 10, the intensity of this 

 shock may be represented by 8. The shock was distinctly 

 double^ and the noise and vibrations accompanying it are 

 described as very loud and violent, both as observed within 

 houses and in the open air. Twelve shocks are said to have 

 been felt in the course of the day ; the weather was cold 

 and inclined to stormy, at the time of this occurrence, and 

 for a day or two before and after. The trees in the neigh- 

 bourhood of Comrie are described as much agitated. The 

 shock was felt eastward, at least as far as Newburgh, about 



