On Architecture

2. It will also do no harm to insert posts between lintels and sills where there are piers or antae; for where the lintels and beams have received the load of the walls, they may sag in the middle, and gradually undermine and destroy the walls. But

3. We must also manage to discharge the load of the walls by means of archings composed of voussoirs with joints radiating to the centre. For when arches with voussoirs are sprung from the ends of beams, or from the bearings of lintels, in the first place they will discharge the load and the wood will not sag; secondly, if in course of time the wood becomes at all defective, it can easily be replaced without the construction of shoring.

4. Likewise in houses where piers are used in the construction, when there are arches composed of voussoirs with joints radiating to the centre, the outermost piers at these points must be made broader than the others, so that they may have the strength to resist when the wedges, under the pressure of the load of the walls, begin to press along their joints towards the centre, and thus to thrust out the abutments. Hence, if the piers at the ends are of large dimensions, they will hold the voussoirs together, and make such works durable.