and especially in Scotland. 157 



shock of 23(1 October 1839 occurred, Mr Williamson of Lawers, 

 bethought himself of instantly examining the state of the ba- 

 rometer. He found that it had fallen a whole inch since the 

 forenoon of the same day when he had set it, — ^being an interval 

 of ten hours. Struck with this circumstance, Mr Williamson 

 continued for about two hours after the shock, that is, till after 

 midnight, to watch the barometer. During that time it still 

 continued falling, but after Ihaly it began to rise, and continued 

 to rise all next day. 



The observation thus made by Mr Williamson is of import- 

 ance, on account of its being made within two miles of the very 

 spot where the shocks are most intense ; and it is fully con- 

 firmed by the returns obtained from more distant places. The 

 following hourly barometric heights shew, that, at Kingussie, 

 (about 50 miles north of Comrie, and 700 feet above the sea)^ 

 the atmospheric pressure was least about 1 a.m. on the 24th 

 October : — 



1839. 



At Inverness, the barometer, which is there also hourly re- 

 gistered for the British Association, began to fall at 4 a. m. on 

 the 23d October, and reached its minimum about 5 p. m., but 

 had risen again only .044 when the shock was felt. 



The barometric registers kept at Dollar Academy (30 miles 

 SE. of Comrie), and at the Cameron (50 miles SW. of Com- 

 rie) which state the atmospheric pressure at a fixed hour every 

 morning and evening, also agree in shewing that the barome- 

 ter was lower on the night of the 23d October than it was 

 in the forenoon of that day, or for some days before and 

 after it. 



Thus, then, it appears that, when the shock of 23d October 

 1839, or rather the series of shocks of that night occurred, the 



