completely supported on iron. These vaults should have the joints on their upper side daubed with clay mixed with hair, and their under side, facing the floor, should first be plastered with pounded tile mixed with lime, and then covered with polished stucco in relief or smooth. Vaults in hot bath rooms will be more serviceable if they are doubled; for then the moisture from the heat will not be able to spoil the timber in the framework, but will merely circulate between the two vaults.
4. The size of the baths must depend upon the number of the population. The rooms should be thus proportioned: let their breadth be one third of their length, excluding the niches for the washbowl and the bath basin. The washbowl ought without fail to be placed under a window, so that the shadows of those who stand round it may not obstruct the light. Niches for washbowls must be made so roomy that when the first comers have taken their places, the others who are waiting round may have proper standing room. The bath basin should be not less than six feet broad from the wall to the edge, the lower step and the "cushion" taking up two feet of this space.
5. The Laconicum and other sweating baths must adjoin the tepid room, and their height to the bottom of the curved dome should be equal to their width. Let an aperture be left in the middle of the dome with a bronze disc hanging from it by chains. By raising and lowering it, the temperature of the sweating bath can be regulated. The chamber itself ought, as it seems, to be circular, so that the force of the fire and heat may spread evenly from the centre all round the circumference.
CHAPTER XI
THE PALAESTRA
1. Next, although the building of palaestrae is not usual in Italy, I think it best to set forth the traditional way, and to show how they are constructed among the Greeks. The square or ob-
