of Edinburgh Session 1880-81. 
185 
times at which the shock was felt as later than that reported from 
Phladda. Three of the Irish reports which I was enabled to inquire 
into, at Omagh, Belfast, and Armagh, give times which agree almost 
exactly with those which might be expected on the assumption that 
the wave felt at those places had been propagated direct from 
Phladda ; and it is therefore probable that the earthquake dis- 
turbance in Scotland and Ireland proceeded from one and the same 
cause. But it is not a little remarkable that in and around Leter- 
kenny “ rumbling noises ” were heard which, as already pointed out, 
were only heard in Scotland within a radius of 38 miles of the 
source, and the shock was also more severely felt than would have 
been expected in a spot removed so far from the source. This I 
think can only be accounted for on the hypothesis that the arrival 
of the earthquake wave from Scotland, generated in the neighbour- 
hood of Leterkenny a second source of disturbance (not at all an 
improbable event), the effects of which were only local. The exact 
time, however, of this disturbance has unfortunately not been 
determined, as the reports from the north of Ireland are not 
sufficiently exact. 
Having thus laid before the Society at some length the facts, so 
far as I have beeirable to ascertain them, regarding this very marked 
earthquake phenomenon, I have only to add in the form of a digest 
some of the principal conclusions to which this investigation 
appears to lead. 
1. That the earthquake occurred in the month of November, a 
month in which many of the British earthquakes are recorded to 
have happened. 
2. That it occurred after a wet period which had been preceded 
by an unusually dry summer and spring. That there was a wide- 
spread thunderstorm at the time, and that the barometer was rising 
slowly over the greater part of the west of Scotland, the average 
height of the barometer at the lighthouse stations at which the 
earthquake was felt being at 9 a.m. 29*4 inches, and at 9 p.m. 
2 9 '5 inches: The thermometer at 9 a.m. averaged 50° F. and at 
9 p.m. 48° F. 
3. That the seismal area was about 19,000 square geographical 
miles, the shock having been felt as far north as the Butt of Lewis, 
as far south as Armagh in Ireland, as far east as Blair Atholl. and as 
