healthy person, at about 98 deg. Fahr., and rises but a few points even
when submitted to the action of heat, these exhalations, in addition to
being heavier than air, are very much below the average temperature of a
sudatory chamber. Consequently they fall, and must be extracted at the
floor level.

The total area of the outlets for vitiated air should be about equal to
the area of the narrowest part of the shaft that conducts the fresh, hot
air from the heating chamber. Thus, supposing the latter to be 5
superficial feet, and the size of outlet ventilators a clear 12 in. by 3
in., there may be 20 ventilators disposed round the bath-rooms, say 4 in
the calidarium, 7 in the tepidarium, and 9 in the combined shampooing
room and lavatorium.

In the diagrams at Figs. 8 and 9 the foul-air conduit is the space
comprised under the marble-topped benches running round the hot rooms.
At the end of the laconicum they enter flues, which I have shown as
running side by side with the smoke flues.

Other methods of heating the air, besides those mentioned, include coils
of iron flue-pipes in a brick chamber--a principle that has been
frequently adopted in the past--and plain cylindrical iron radiating
stoves, such as employed at the Hammam in Jermyn Street.

[Illustration: FIG. 9.

Section of Hot Room, showing Foul-air Conduit.]

In the latter plan, however, a great expense is created by the large
number of furnace-fires to be kept constantly burning. An exposed stove
in a hot room, has, moreover, the objection to its use that it re-heats
the air in the bath, which should never on any account be done.

If the iron stove-pipe system is adopted, a furnace similar to the one
shown at Fig. 10 must be provided, and after an additional few feet of
brick flue the iron pipe would commence and turn back upon itself much
as the flue in the fire-brick furnace. Proper supports must be
provided, and the pipes must be stout and jointed together with
expansion joints, otherwise considerable difficulty will be found in
keeping a long length of flue pipe perfectly free from leakage. Furnaces
on this principle may be designed so that they throw a certain amount of
radiant heat direct into the hot-rooms, and they possess this advantage
over a mere stove, that they warm the air more gradually. The furnace
should be built adjoining the laconicum, the partition wall being of
4-1/2-inch glazed brickwork, having a large number of small openings
mad