[Picture: Fig. 15: Section through the subsided floor]
We see in these three sections, and in several others not given, that the
old pavements have sunk or sagged considerably. Mr. Joyce formerly
attributed this sinking solely to the slow settling of the ground. That
there has been some settling is highly probable, and it may be seen in
Fig. 15 that the pavement for a width of 5 feet over the southern
enlargement of the room, which must have been built on fresh ground, has
sunk a little more than on the old northern side. But this sinking may
possibly have had no connection with the enlargement of the room; for in
Fig. 13 one half of the pavement has subsided more than the other half
without any assignable cause. In a bricked passage to Mr. Joyce s own
house, laid down only about six years ago, the same kind of sinking has
occurred as in the ancient buildings. Nevertheless it does not appear
probable that the whole amount of sinking can be thus accounted for. The
Roman builders excavated the ground to an unusual depth for the
foundations of their walls, which were thick and solid; it is therefore
hardly credible that they should have been careless about the solidity of
the bed on which their tesselated and often ornamented pavements were
laid. The sinking must, as it appears to me, be attributed in chief part
to the pavement having been undermined by worms, which we know are still
at work. Even Mr. Joyce at last admitted that this could not have failed
to have produced a considerable effect. Thus also the large quantity of
fine mould overlying the pavements can be accounted for, the presence of
which would otherwise be inexplicable. My sons noticed that in one room
in which the pavement had sagged very little, there was an unusually
small amount of overlying mould.
As the foundations of the walls generally lie at a considerable depth,
they will either have not subsided at all through the undermining action
of worms, or they will have subsided much less than the floor. This
latter result would follow from worms not often working deep down beneath
the foundations; but more especially from the walls not yielding when
penetrated by worms, whereas the successively formed burrows in a mass of
earth, equal to one of the walls in depth and thickness, would have
collapsed many times since the desertion of the ruins, and would
consequently have shrunk or subsided. As the walls cannot have sunk much
or at all, the immediately adjoining pavement from adhering to them will
have been prevented from subsiding; and thus the present curvature of the
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