On Architecture

2. The hanging floors of the hot bath rooms are to be constructed as follows. First the surface of the ground should be laid with tiles a foot and a half square, sloping towards the furnace in such a way that, if a ball is thrown in, it cannot stop inside but must return of itself to the furnace room; thus the heat of the fire will more readily spread under the hanging flooring. Upon them, pillars made of eight-inch bricks are built, and set at such a distance apart that two-foot tiles may be used to cover them. These pillars should be two feet in height, laid with clay mixed with hair, covered on top with the two-foot tiles which support the floor.

3. The vaulted ceilings will be more serviceable if built of masonry; but if they are of framework, they should have tile work on the under side, to be constructed as follows. Let iron bars or arcs be made, and hang them to the framework by means of iron hooks set as close together as possible; and let these bars or arcs be placed at such distances apart that each pair of them may support and carry an unflanged tile. Thus the entire vaulting will be

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.