Suspensurae caldariorum ita sunt faciendae, ut primum sesquipedalibus tegulis solum sternatur inclinatum ad hypocausim, uti pila cum mittatur, non possit intro resistere, sed rursus redeat ad praefurnium ipsa per se; ita flamma facilius pervagabitur sub suspensione.
The vaulted rooms that hold the basins are to be warmed using the furnace. The suspended levels of the warm baths will be constructed in the following manner: Initially, the ground will be paved with eighteen inch tiles that angle towards the furnace. This is done so that when a ball is tossed inside, it does not remain within, but automatically bounces back to the furnace space. As a result, the fire will be able to spread easily beneath the floor.