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.