‹‹‹ Vitr. 2.7.4 | Table of Contents | Vitr. 2.8.1 ›››
5But as necessity, on account of proximity to the quarries, obliges us to use the red sort of stone, that of the Pallienses and other species in the immediate vicinity of the city, in order to find that which is least defective, let it be selected as follows. Two years before the commencement of the building, the stones should be extracted from the quarries in the summer season; by no means in the winter; and they should then be exposed to the vicissitudes and action of the weather. Those which, after two years’ exposure, are injured by the weather, may be used in the foundations; but those which continue sound after this ordeal, will endure in the parts above ground. These rules apply equally to squared as to rubble or unsquared stone work.
5But since, on account of the proximity of the stone-quarries of Grotta Rossa, Palla, and the others that are nearest to the city, necessity drives us to make use of their products, we must proceed as follows, if we wish our work to be finished without flaws. Let the stone be taken from the quarry two years before building is to begin, and not in winter but in summer. Then let it lie exposed in an open place. Such stone as has been damaged by the two years of exposure should be used in the foundations. The rest, which remains unhurt, has passed the test of nature and will endure in those parts of the building which are above ground. This precaution should be observed, not only with dimension stone, but also with the rubble which is to be used in walls.