190 The East Anglian Earthquake.
53. London ........9 h. 17 m. (Railway time). Haverstock Hill; Mr.
A. B. Woodd (p. 141).
54. Do.........9h. 20 m. (- 1 or 11/2m.). Leadenhall Street; Mr.
E. Gellatly (p. 145).
55. Beckenham ___9h. 20 m. Mr. J. Moore (p. 149).
56. Chislehurst ....9h. 18m. Mrs. A. Oldham (p. 149).
57. Greenwich......9 h. 20 m. (Royal Observatory). Mr. W. Ellis (p. 150).
58. Kew Observatory..9 h. 17 or 18m. (G.M.T.). Mr. G.M.Whipple (p.152).
59. Lee............9 h. 19 m. 30 s. Holly Bank, Burnt Ash Hill (p. 151).
60. Richmond......9 h. 20 m. Mrs. Hertslet (p. 152).
61. Eastbourne ___9h. 20m. Mr. L. Dyer (p. 153). [154).
62. Boulogne ......9 h. 20 m. 39 s. (G.M.T.). Mr. Symons's report (p.
Of these records, the greatest weight attaches to Nos. 1, 5,
9, 11, 12, 16, 25, 27, 31, 34, 35, 36, 38, 42, 43, 48, 52, 57,
58, 59, and 62. The tendency to make the time exactly 9.20
is most probably due to the "personal equation" which causes
most people to fix the time of an event at the nearest whole
division of the hour. The disturbance probably occurred at
the epicentrum between 9h. 17 m. and 9h. 18 m. G. M. T.
Of the selected records, No. 35 gives the time within 10
seconds, and No. 36 within 20 seconds.
Velocity.—(A.) Assuming No. 35 to be correct, and taking
the time of the shock at Claydon as 9h. 17 m. 50 s., the dis-
turbance reached Norwich, according to No. 43, at 9 h. 18 m.,
or in 10 seconds. The distance from Claydon to Norwich is
37 miles, giving a velocity of propagation of 19,536 feet per
second.
(B.) The mean of all the London observations is about
9h. 18 m. 25 s. (Nos. 47 to 54). Taking Peldon as a centre,
and describing an isoseismal circle passing through London,
the distance from this circle to Boulogne, measured along a
line connecting Peldon and this last place, is 35 miles. This
distance, assuming the correctness of the Boulogne record
(No. 62), was traversed by the disturbance in 2m. 14s., giving
a velocity of 1379 feet per second. If record No. 48 be taken
as of the greatest weight, the time of propagation becomes
69 seconds, and the velocity 2678 feet per second. The mean
of the two velocities is 2028.5 feet per second.
(C.) Assuming records Nos. 1 and 38 to be correct, the
movement travelled from Colchester to Ipswich, a distance of
about 17 miles, in 15 seconds, corresponding to a velocity of
5984 feet per second.