62 C. Davison — British Earthquakes. 



kindness and courtesy of Dr. C. B. Gunn, of Peebles wlio, at the 

 cost of much time and trouble, sent me a report on the observations 

 of the earthquake made in and near the north of Peeblesshire. I 

 shall have occasion to refer again to this report, the value of which 

 it would be difficult to over-estimate. 



The outline of the disturbed area as drawn upon the accompanying 

 map, is slightly elliptical in form. How far this outline may be 

 considered as accurate will be partly evident from an inspection of 

 the map, on which all places at which the shock was certainly felt are 

 marked with small black discs, and those where there is good reason 

 for believing that it was not felt with small crosses (-1-).^ There can 

 thus be little doubt about the form of the boundary from the neigh- 

 bourhood of Polmont, by Dumfermline, Burntisland, Musselburgh, 

 and Tynehead station, to Peebles ; but, for the rest of the area, its 

 course is less certain. I have made several inquiries in this part of 

 the district, but entirely with negative results. From the intensity 

 of the shock at the neai'est places at which it was felt, I do not think, 

 however, that the form of the boundary can differ very greatly from 

 that laid down on the map, unless, owing to peculiar local conditions, 

 the earth-vibrations were quenched more rapidly in the south-west 

 quarter than elsewhere. 



The disturbed area as thus defined is about 30 miles from north 

 to south and 26^ miles from east to west, and contains an area 

 (including the part occupied by the Firth of Forth) of about 830 

 square miles. Its boundary corresponds to an isoseismal line of 

 intensity less than V., but decidedly greater than IV. The centre 

 of the curve is about 3 miles W. 42° S. of Balerno. 



It is worthy of notice that in Edinburgh, where the intensity was 

 v., the shock was not felt by any one on the Castle Hill, nor at 

 the Observatory on Calton Hill. The geological structure of the 

 district may also account for the shock not having been felt at 

 Inchkeith, and not having been recorded as felt within a large part 

 of the area occupied by the Pentland Hills. 



Time of Occurrence. — Omitting all confessedly approximate deter- 

 minations of the time of occurrence, the following definite records 

 have been made : Edinburgh, 6h. 50m., 6h. 52m., and 6h. 54m. 

 or 6h. 55m. ; Penicuik, 6h. 52m. ; Leith, 6h. 53m. 15s. ± 10s. ; 

 Trinity (near Leith), 6h. 54m. ± -^m. ; Harperrigg and Peebles, 

 6h. 55m. These estimates, with one exception, are not exact 

 enough to be used for ascertaining the velocity of the earth- wave or 

 the position of the focus. Probably the most correct of these times 

 is that given for Leith; it was determined by Mr. G. Eedpath. " I 

 immediately turned round," he says, " and noted the time, which I 

 found was 53 minutes 15 seconds past six by a clock in my sitting- 

 room. On going to verify it by an astronomical clock in another 

 room, I found to my regret that I would have to allow a margin of 

 about ten seconds — earlier or later." This is sufficient, however, 



1 To the south of Peebles, owing to the small scale of the map, I have been 

 obliged to omit the indication of a number of places where, as Dr. Gunn's inquiries 

 show, the shock was not felt. 



