vault, if there was one, over the semi-circular _exedrae_ must have
been hemispherical. From the number of roofing tiles of local stone,
shaped into hexagons, found, I think these arcades were roofed in
with them, placed overlapping each other, giving a very good effect.
Similar tiles were dug up at Wroxeter, and I have found slates of the
same shape in the Roman villa I have been excavating for Mr. Chas. I.
Elton, F.S.A., M.P., at Whitestaunton Manor. The form of these slates
deserves copying; a roof covered by them is far lighter than that of
rectangular slabs and more picturesque. The walls on the sides towards
the hall, and externally, so far as I have been able to ascertain, are
covered with the usual red plaster, shewing that they were internal
walls; but from a piece of dentilled, or rather blocked, cornice,
which fits the curve of one of the _exedrae_, I believe the walls were
carried up on the north and south above the roofs of the adjoining
rooms and corridors of the baths, so that they formed a feature in the
elevation and afforded a broken skyline to the composition. The vault
over the centre rose considerably above these walls, a portion of the
centre of which may have been partially open for the emission of steam
and the admission of light. Some square blocks of lead, that were the
yotting of bars of metal, rather favour this idea, and suggest that
these metal bars were a portion of the machinery by which a brazen
shield (_clipeus_) was suspended, or secured, so that by raising
or lowering it the temperature of the hall might be regulated as
described by Vitruvius. In the excavations we found an _ante-fixa_
that must have fallen from some portion of the roof. It appears to
be intended for a lion, but it is much broken.

I have prepared a sketch section of the bath (which I hope
to communicate on a future occasion), transversely and a part
longitudinally, in order that a description may the more readily be