Vol. 58.] INVERNESS EARTHQUAKE OF SEPTEMBER 1901. 389 
isoseismal 6, and the isoseismal 7 approximately. Outside the 
isoseismal 5, records of the shock are scanty; but the intensity 
was 4 as far as Lochluichart, which is 22 miles north-west of the 
epicentre and 13 miles from the isoseismal 5. A shock was also 
reported at about 4 a.m. from Crathes (Kincardineshire); but, 
as that locality is 74 miles from the epicentre, the connection 
between this disturbance and the earthquake under consideration 
is doubtful. 
The isoseismal 7, which is only roughly drawn, is 5 miles long, 
21 miles wide, and contains about 10 square miles. Its centre is 
2 miles south-by-west from Dochgarroch, and half a mile on the 
south-east side of the fault. The isoseismal 5 is 33 miles long, 
23 miles wide, and 595 square miles in area: its longer axis 
running N. 34° E. and 8. 34° W. The distance between the iso- 
seismals 7 and 5 is 8 miles on the north-west, and 121 miles on 
the south-east side. The originating fault. must therefore run 
N. 34° E. and S. 34° W., and must hade to the south-east. The 
closeness of the epicentre to the line of fault shows that the depth 
of the seismic focus must have been very small; and the rapid 
decrease in the intensity of the vibrations as they radiated outward 
points to the same conclusion. 
The shock, the mean duration of which was 3 seconds, differed in 
one respect from those that preceded it. The movement at Inchmore 
(Kirkhill) was distinctly more lateral, more undulating or swinging, 
than in the others. At Inverness one observer remarks that the 
movement was horizontal, as distinguished from the vertical or 
* choppy-sea’ motion of the principal shock. 
The sound was heard by at least 80 per cent. of the observers. 
It was compared to passing waggons etc. in 25 per cent. of the 
records, to thunder in 50 per cent., wind in 4, loads of stones falling 
in 4, explosions in 8, and miscellaneous sounds in 8 per cent. The 
beginning of the sound preceded that of the shock in 61 per cent. 
and coincided with it in 39 per cent. of the records; while the end 
of the sound preceded that of the shock in 16 per cent. of the 
records, coincided with it in 28, and followed it in 56 per cent. 
The duration of the sound was greater than that of the shock in 
64 per cent. of those records in which the time-relations of both 
terminal epochs are given, was equal to it in 18 per cent., while in 
the remaining 18 per cent. the relative duration of the sound and 
shock is doubtful. 
September 30th, about 4.10 a.m.: Aldourie.—A slight shock. 
o. October Ist, about 4.85 a.m. 
Intensity, 5. Number of records 2, from 2 places. 
A shock, preceded, accompanied, and followed by a sound like 
thunder, was felt at Dalarossie and Coignafuinternach. 
October 1st, about 3p.m.: Dalarossie.—A faint sound, like 
distant thunder, was heard, withont any shock. 
Q. J.G.8. No. 231. 2 
