183 
of Edinburgh, Session 1880-81. 
situated on the older formations (Laurentian, Cambrian, and Meta- 
morphosed Lower Silurian), eleven felt the shock, whilst of thirteen 
observers situated on newer rocks, it made itself known only to two 
of them, and it may therefore be assumed that it was more sensibly 
developed on the older rocks of Scotland than on those of more 
recent formations. Judging from the times of occurrence of the 
earthquake, I think I am warranted in coming to the conclusion 
that the seismal focus was situated near Phladda lighthouse, which 
it may be remarked lies nearly in the line of the great fracture which 
runs from Inverness through Scotland in a south-westerly direction. 
It may be interesting to notice that the earthquake shocks of 1877, 
communicated by Mr David Stevenson, had their origin in the same 
district, having been experienced at Phladda, Hynish, Sound of 
Mull, and Lismore. 
Stations. 
Distance 
from Source 
in Geog. 
Miles. 
Calculated 
Velocity- 
in Miles 
per Minute. 
Inverary, 
34 
3 '9 mean 
Land Joueneys.* 
Skerryvore, 
38 
6-4 
Inverary, Kyleakin, 
Ayr, .... 
63 
6-3 
Motherwell, Blair Atholl, 
Armagh, and Omagh, — 
Kyleakin, . 
69 
4-0 
mean velocity 4 ’65 miles 
per minute. 
Motherwell, 
75 
375 
Sea Joueneys. 
Blair Atlioll, 
84 
5-6 
Skerryvore, Ayr, Mo- 
Monach and Ushenish, 
90 
7 '5 mean 
nach and Ushenish, Bel- 
fast, and Island Glass, 
Belfast, 
91 
7-0 
— mean velocity 674 
miles per minute. 
Island Glass, 
104 
6-5 
Omagh, . 
105 
5-25 
Armagh, . 
108 
5-4 
The exact focus, however, is not certain, but as a centre from 
which to calculate the velocity, a point has been chosen lying S.S.W. 
* If the wave in its course passed over a greater extent of land than of sea, it 
has been classified as a land journey, and vice versa. 
VOL. XI. 2 A 
