TRANSACTIONS OF THE SECTIONS. 97 
On Earthquakes in Scotland. By D. Mitye, F.R.S.E. 
Since the year 1788, shocks have been remarked, and have been 
partially registered. Three-fourths of these seem to have issued from 
Comrie, in Perthshire, and most of the others from the banks of Loch 
Ness. The district of Comrie contains mica-slate, clay-slate, and gray- 
wacke, with hills of granite and compact felspar, which have elevated 
the other rocks, the conglomerate of the graywacke containing no peb- 
bles of granite or felspar; but on the former rocks is old red sand- 
stone, containing these pebbles. There are also some remarkable green- 
stone dykes, which seem to run parallel to each other from sea to sea, 
in east and west direction, and cutting the oldest and newest strata. 
The shocks emanated from a granite hill, or from the junction between 
it and clay-slate, about two miles from Comrie. In October 1839, there 
were sixty-six shocks; November, twenty-one; December, nineteen ; 
January 1840, eight; February, six; March, thirteen; April, eight; 
May, five; July, six; the severest being on the 23rd of October, at 
half-past ten p.m. It was felt as far north as Lochaber and Dingwall, and 
as far south as Carlisle and Coldstream ; varying in intensity in different 
places. The shocks appear to come from a central point, as their di- 
rection is different at different places ; at Comrie being from the north, 
at Dunkeld from the south-west, and at Loch Earn Head from the east. 
There was an upward motion at Comrie, and at other places it was ob- 
lique. There was, likewise, a diminution of intensity and sound as the 
distance from Comrie increased ; and there was, in each place, a marked 
difference in the damage done to houses. The shock was more se- 
verely felt where the soil was alluvial; although, in this case, the sound 
was not heard, as in rocky places. Occasionally there was a fall of 
fine black powder, and in some places there was a sensible smell. Va- 
rious explanations may be given as to the rationale of these shocks ; 
but one of the readiest is, the passage of water down to some heated 
mass below, and its consequent conversion to steam. As bearing on 
this, the shocks are found to have been more frequent at the time of 
the year when the greater quantity of rain falls, and when the baro- 
meter is lowest. During the last fifty years, 198 shocks took place in 
the winter half-year, and sixty-one in the summer. At the present 
time, observations are carefully taken with instruments for the purpose. 
D. Milne, Esq., in the absence of Lord Breadalbane, stated the sub- 
stance of a notice respecting the metalliferous veins of Tyndrum, in 
which a great variety of metals has been found. 
Lord Greenock announced the discovery of lead on the estate of his 
brother, Colonel Cathcart, on the borders of Galloway and Ayrshire. 
The vein runs N.N.E. and S.S.W.; it is far distant from granite. It 
contains five ounces of silver to the ton. There is hematitic iron ore in 
the vicinity. 
1840. H 
