Vol. 58.] THE CARLISLE EARTHQUAKES OF 1901. 371 
23. The Cartiste Eartaeuakess of Jury 9a anv l1rn, 1901. 
By Cuartes Davison, Sc.D., F.G.S. (Read April 16th, 1902.) 
[Map on p. 372.] 
Tue chief title to interest possessed by the Carlisle earthquakes of 
1901 is the light which they throw upon the structure of the 
region underlying the Lake District and the North of Cumberland 
—a structure which must clearly be very different from that mani- 
fested by the surface-rocks. The shocks were at least four in 
number. ‘The first and strongest occurred on July 9th, at 4.23 P.M. ; 
the second about three minutes later; the third on the same day at 
4.45 p.m.; and the fourth on July 11th at about 11.10Ppm. In 
addition, there are records of four other shocks, depending on the 
authority of single observers. These are as follows :— 
July 9th, about 3 p.m.: Loweswater. A slight shock. 
July 10th, about 1.30 a.m.: Crosthwaite (near Keswick). A 
slight shock without sound. 
July 12th, about 2 a.m.: Crosthwaite. The same. 
July 14th, about 11 p.w.: Crosthwaite. The same. 
a. July 9th, 4.23 p.m. 
Intensity, 5 centre of isoseismal 5, lat. 54° 47-8’ N., long. 3° O-4' W. 
Number of records 267, from 155 places; and negative records from 50 
places. 
Isoseismal lines and disturbed area.—The two continuous 
curves in the map (p. 372) refer to this earthquake. The isoseismal 
5 is very nearly a circle, 29 miles in diameter, and 660 square miles 
in area. Its centre is situated at a point 7 miles south-south-west 
of Carlisle. 
The isoseismal 4 is an elongated ellipse, 66 miles long, +6 miles 
wide, and 2390 square miles in area, its longer axis running 
N. 5° E., and 8. 5° W. The distance between the isoseismals 5 
and 4 is 5 miles on the west side and 10 miles on the east. 
Outside this isoseismal, the shock was felt at Whitehaven, 2 miles 
to the west, Westerkirk and Eskdalemuir, respectively 4 and 9 
miles to the north, and Barbon, near Kirkby Lonsdale, 5 miles to 
the south-east. Its disturbed area must therefore have contained 
more than 3000 square miles. 
The excentricity of the isoseismal 5 with respect to the iso- 
seismal 4 is the most peculiar feature of these lines. On the north, 
the distance between them is 10 miles, and on the south 27 miles, 
the distance between their centres being about 9 miles. 
Nature of the shock.—In the central portion of the dis- 
turbed area, the shock consisted of a single continuous series of 
vibrations. The accounts as a rule are not very detailed, but 
