Appendix. 219
corner to a sufficient extent to allow the blade of a knife to be
inserted between the stone and its bedding. B and C were
not tilted, but they may have been slidden along the surface
of the timber balk on which they rested. The only other
explanation of this displacement is that the whole floor had
moved northwards; but if this had been the case we should
have expected to find that the planks had started away from
the wall of the Observatory somewhere on the southern side.
A careful examination failed, however, to reveal any such
shift of the floor, and we concluded therefore that it was the
piers which had been shifted.
The particular character of the displacement described does
not give any distinct indication of the prevailing direction of
the movement at Crowborough, but the fact that the stone at
A was tilted up at its N.E. corner agrees exactly with the
supposed direction from which the disturbance travelled
towards this place. We may point out that the shock itself
was actually felt here and in several other parts of Sussex
(p. 153), and the position of the telescope, a massive instru-
ment standing in the highest part of a building at a height of
thirty-four feet above the ground, was eminently favourable
for taking up any vibrations communicated from the ground
to the building.113
Appendix.
British Earthquakes.
Since presenting the foregoing Report to the Essex Field
Club, a short paper on the earthquake of 1884 has been
published by Mr. Horace B. Woodward, F.G.S., of the
Geological Survey, in the ' Transactions of the Norfolk and
Norwich Naturalists' Society,' vol. iv., pp. 31-35 (read
Nov. 25th, 1884). Mr. Woodward makes the following
statement:—
"Probably we shall not be far wrong if we attribute the
recent earthquake in Essex to one or more subterranean
rents produced by shrinkage, which led to no material shifting
of the rocks, and which, owing to the tenacious nature of the
113 The drawings from which the figures 17 and 19 are produced were
made carefully to scale for me by Mr. Symons. Fig. 18 is from a wood-
block kindly lent by Mr. Prince