antage, in point of ease and economy, to be
able to warm a building, drive machinery, and heat Turkish and Russian
baths from one boiler, which can readily be done, very ordinary
pressures of steam giving sufficient heat to keep the radiators of the
requisite temperature. But the nature of the heating accomplished by
means of steam-pipes is very inferior to that from large radiating
surfaces of firebrick.

The average temperatures of a public bath should range from about 110 deg.
in the shampooing rooms to 250 deg.-260 deg. in the hottest part of the
laconicum, taking the readings of the thermometer at a level of 6 ft. 6
in. above floor-line. Between the entrance of the heated air and its
point of furthest travel in the shampooing rooms, the bather should be
able to select any temperature that may be most agreeable to him, and as
many find by experience that a certain degree of heat is best suited to
themselves, it shows attention to the _habitues_ of the bath, if the hot
rooms are carefully maintained at the same uniform temperatures
throughout the year. This may be 110 deg.-120 deg. in the shampooing rooms, 140 deg.
in the tepidarium, 180 deg. in the calidarium, and 250 deg. in the laconicum.
These must be the maxima of the average temperatures of each room at 6
ft. 6 in. above the floor. In a pure atmosphere the highest temperatures
are comfortable, but in a foul one they become insupportable.

In a good bath, where there is a rapid and continuous flow of air, there
will be comparatively little difference between the temperature at say 4
ft., 6 ft., and 8 ft. above the floor. In badly-ventilated rooms, where
the air stagnates, there will be a considerable difference. And here we
may note a serious objection to the heating of a bath by convection; for
while the head may be in a high degree of heat the feet are in
comparatively cool air, whereas, if possible, it should be just the
reverse. In convected heat, this of course applies in its entirety, as
where so-called radiant heat is employed the evil is not quite so
marked. And here, too, we may note the admirable nature of the Roman
system of heating, where the floors radiated the majority of the heat,
and the walls a slightly less amount. The fresh air under the ancient
system must have entered through the cooler rooms, and being drawn
towards the _calidarium_ found its exit through the ceilings, at times
by way of the regulating device mentioned by Vitruvius. Thus th