and especially in Scotland. 101 



to produce simply a contact, but no pressure of the wall?, at 

 the height of 11 feet from the ground. If then, this deviation 

 is to be ascribed to a rising of the ground, such as would beT 

 caused by the propagation of a wave along the earth's surface, 

 the surface must have inclined or sloped to at least the extent 

 of the above angle, so that the wave must have formed with 

 the horizon an angle of more tlian 1° 18'. 



But is it a probable supposition, that one of the walls would 

 remain stationary, whilst the other leaned towards it .^ If the 

 wave came from the north, the glass-house wall would, no 

 doubt, be first affected ; but would not the back wall of the 

 watch-house be also made to lean over almost simultane- 

 ously ? It is true that the two walls were at the foundations 

 only 4 inches apart ; but then the back wall of the watch- 

 house formed one side of a solid building, abutting against 

 two gables 14 feet long. The back wall of the watch-house, 

 therefore, would probably not move until the wave had ad- 

 vanced far enough to affect the whole building. Moreover, 

 it is plain, that the house would not by the supposed wave 

 coming from the north, lean over so much as the glass-house 

 wall. A wall at right angles to the course of a wave would 

 deviate from the perpendicular, whilst a wall running in the 

 direction of the wave would scarcely rise at one end and be 

 depressed at the other, but would, if at all affected, be rent. 

 In this way it may be understood how the back wall of the 

 watch-house abutting against the north ends of the gables 

 would remain vertical, and would be reached by the upper part 

 of the glass-house wall as it leaned over. 



(7.) Accounts from Districts South of Comrie. 



On the south side of the Forth, and at Airth, nearly oppo- 

 site to Alloa, about nine miles east of Stirling, the concussion 

 was felt as one undulation or heave, with but little noise. 



At Throsk house, about four miles east of Stirling, situated 

 in the low flat Carse land, only seventeen feet above high-water 

 mark, effects, in some respects similar, were observed. Mr 

 Jeffrey, " whilst sitting at a writing-desk, was suddenly moved 

 forward by a very heavy undulation, which I immediately con- 



