Descriptive Report. 105
of a bedstead were seen to slide along about two feet. Doors
were opened, and a clock with pendulum swinging N. and S.
was stopped at Jacob's Farm. Time given as 9.19. At the
Heybridge Ironworks, Messrs. E. H. Bentall and Co., a large
T-square hanging against a wall was observed to swing, and
Mr. E. A. Fitcb, at my request, has been good enough to
supply the following particulars, furnished by Mr. H. Hurrell,
who was in the drawing-office at the time, and observed the
movement, and who states that he was much impressed by
the occurrence. Mr. Hurrell reports as follows :—
" The office stands as shown below in a rough sketch,
nearly N.N.E. and S.S.W., and the square, which is 48
inches long, hung on the main beam a.
Fig. 13.—Ground-plan of Office ; a a, Main beam, b, position of
T-square. Length c. .d, 48 inches; arc of oscillation (chord) a., b, about
10 or 11 inches. The T-square and dotted lines are not drawn to scale.
" It began to swing quite two or three seconds before I felt
the shock and before the windows rattled in the casements.
I am also nearly certain that the square started from N.N.E.
to S.S.W., swinging when at its greatest arc 10 or perhaps
11 inches, and was quite three quarters of a minute before
it regained its former steadiness. This latter fact of course
shows nothing, as the T-square acted as a pendulum. The
position of the office is exact by compass; the square hung
on a nail three inches from beam."
The foregoing observation is of considerable importance, as
showing that the movement of the wall (and building) was
nearly E.N.E. and W.S.W., and that the disturbance pro-
bably came from the former direction. It is particularly