‹‹‹ Vitr. 1.5.2 | Table of Contents | Vitr. 1.5.4 ›››
3The thickness of the walls should be sufficient for two armed men to pass each other with ease. The walls ought to be tied, from front to rear, with many pieces of charred olive wood; by which means the two faces, thus connected, will endure for ages. The advantage of the use of olive is, that it is neither affected by weather, by rot, or by age. Buried in the earth, or immersed in water, it lasts unimpaired: and for this reason, not only walls, but foundations, and such walls as are of extraordinary thickness, tied together therewith, are exceedingly lasting.
3The thickness of the wall should, in my opinion, be such that armed men meeting on top of it may pass one another without interference. In the thickness there should be set a very close succession of ties made of charred olive wood, binding the two faces of the wall together like pins, to give it lasting endurance. For that is a material which neither decay, nor the weather, nor time can harm, but even though buried in the earth or set in the water it keeps sound and useful forever. And so not only city walls but substructures in general and all walls that require a thickness like that of a city wall, will be long in falling to decay if tied in this manner.