ovided. These
should run round the solid walls, the risers of the benches being formed
of brickwork--glazed, faced with tiles, or plastered--and white marble
slabs set thereon. These slabs cannot be less than 24 in. wide, and must
be of the ordinary seat height--not lower. In the risers must be
provided a liberal number of "hit-and-miss" ventilator gratings, the
vitiated air finding its way from the space beneath the slabs in the way
designed, which may be into surrounding areas, into hollow walls, or
into a flue or flues running the whole height of the building.

The air at the floor line and that at the ceiling level being of vastly
different temperatures, it follows that an arrangement might be designed
whereby the benches might be stepped in three or four rows, and, by
ascending, the bather could select any temperature he might choose. Such
an arrangement was often employed in the baths of the ancient Romans,
and has been tried in modern institutions; but it should be avoided. The
expirations from the lungs and the exudations from the bodies of the
bathers _fall_, and it therefore follows that all below the first tier
would be breathing air polluted by those above them. The system,
therefore, stands condemned.

As regards height, the sudorific chambers should not be too lofty, or
they cannot, on the ordinary hot-air plan, be heated with due economy.
The vastness of the old Roman tepidarium would have been impracticable
under this system; but with the heat radiating direct from the walls and
the floors, there was no difficulty. It is far better to have a
comparatively low chamber with a constant stream of freshly-heated air
passing through it, than a lofty one with a sluggish current. From 10 to
15 or 16 ft. may be taken as moderate extremes of height in a public
bath. The small third hot room will be less lofty if the heating-chamber
be placed under it; for by raising the floor of the laconicum a few
feet, so as to necessitate ascending to it by a few steps from the level
of the tepidarium, one can more economically construct the furnace
chamber.

This latter, which I have more particularly described and illustrated in
the chapter on heating and ventilation, should, if the system adopted be
on the ordinary hot-air principle, be so placed that an abundant supply
of fresh pure cold air can be obtained for the furnace, which, when
heated, can be delivered into the hottest room above, not less than 5
ft. from the lev