218 The East Anglian Earthquake.
moved round on the conical support at A as a pivot about one
inch in an easterly direction, so that it had to be screwed
back in azimuth the same distance towards the W. in order
to restore it to a proper state of adjustment. The screws
(azimuth) had not been moved for so many years that they
had almost rusted into their sockets, and their old position
was visibly marked by the circle of rust. A further examina-
tion showed that the piers had also been moved southwards
so as to become jammed against the sides of the holes through
which they passed, and they were seen to be no longer
surrounded by the free margin. In the accompanying figure
(Fig. 19) the position of the piers as seen at the time of my
visit is shown by the dotted lines:—
Fig. 19.—Southward displacement of the piers which were formerly
exactly in the centres of the holes through the floor. The letters have
the same meaning as in Fig. 17.
The conclusion that the instrument was shifted by the
earthquake seemed the only possible explanation of the facts,
and we have therefore given the evidence in detail. On
arriving at Crowborough, Mr. Prince was good enough to
have the floor of the Observatory taken up all round the piers
in the presence of Mr. Symons and myself, and it was then
found that the stone slab, A, had been tilted up at its N.E.