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present case,
the flue arch below Rooms 58 and 46 is well preserved because
it was blocked (Plate IIIA), and its top is 2 feet higher than
the bottom of the aperture for the bath drain, leaving room
for a testudo of 2-feet radius. On either side of the testudo
arch, there was a chimney set in the thickness of the wall
(Plate IIIB). On the basis of the testudo tank and the
drain, the height of the hypocaust would have been about 3
feet.
The two chimneys (Plate IIIB), built inside the north-west
wall of Room 58 and intended for the dispersal of smoke and
gases from both the furnace and the hypocaust it served, were
rectangular and quite enclosed within the bonding-tile courses
of the wall: they showed no traces of rendering, which would
have been necessary had they been intended as water conduits,
nor of soot which must have been cleared away when, in Phase
B, the south-east face of the wall was cut back thus exposing
the two chimneys.
A vertical water-conduit (Plate IIIB) was constructed inside
the north-west wall of Room 58; it was rounded, rendered with opus
signinum and contained clay-pipes, the lowest of which
curved beyond the inner face of the wall to project into the
hypocaust space. Clearly, the clay-pipes would be needed as a
shield for the lead-piping, which is assumed to have been
placed inside them in order to feed water from the boiler into
the plunge-bath, passing below the hypocaust and entering the
plunge through an inlet duct, which would have been provided
for this purpose.12 Excavation has provided no
apparent reason for this circuitous way of supplying hot water
to the plunge rather than through a normal inlet directly from
a higher level, but the interpretation suggested above would
seem to fit best the excavated evidence.
The plunge-bath was drained by means of an outflow drain
through its north-west wall (Plate IIIB and
Fig. 1), which had
sides rendered with opus signinum; free-standing
roofing- and bonding-tiles were placed inside this channel to
form the bottom, sides and top of the drain, but no trace
remained either of its lead-piping or its connection with the
plunge, both presumably had been removed and destroyed in the
later reconstruction of the area. The water from this
plunge-bath was drained directly into the main drain, which
the drain from Room 58 joined below the tessellated floor of
Room 51 and a little outside the limits of the excavated area.
Room 46 was the furnace-room supplying both the
hypocaust in Room 58 and heating the water for the
plunge-bath. It measured 11 feet 6 inches by 10 feet 6 inches,
and its walls were of the standard build and thickness (Plates
IIIA and IIIB), except for the wall separating it from Room
58; these walls were constructed inside a rectangular
excavation cut into the subsoil for the purpose of building
the praefurnium
12 I am indebted to Professor S. S. Frere,
V-P.S.A., for visiting the site and discussing with me the
problems of water-supply in this room. |