Of the Choice of Materials.
HE Materials of which Vitruvius speaks are, Stone, Brick, Wood, Lime, and Sand.
All the Stones are not of one sort, for some are soft, some harder, and some extreamly hard.
Those that are not hard are easily cut, and are good for the Inner Parts of the Buildings, where they are cover'd from Rain and Frost which brings them to Powder, and if they be made use of in Buildings near the Sea, the Salt Particles of the Air and Heat destroys them.
Those that are indifferently hard, are fit to bear Weight; but there are some sorts of them, that easily crack with the heat of the Fire.
There is likewise another sort of Stone, which is a kind of Free-Stone; some are Red, some Black, and some White, which are as easily cut with a Saw as Wood.
The best Bricks are those which are only dry'd and not baked in the Fire; but there are many Years required to dry them well: and for this Reason, at Utica, a City of Africa, they made a Law, That none should make use of Bricks which had not been made five Years: For these sort of Bricks, so dry'd, had their Pores so close in their Superficies, that they would swim upon Water like a Pumice-Stone; and they had a particular Lightness, which made them very fit for all sorts of Buildings.
The Earth of which these Bricks were usually made was very Fat, and a sort of White Chalky Clay without Gravel or Sand, which made them Lighter and more Durable; they mixed Straw with them to make them better bound and firmer.
The Woods which were made use of in all Buildings, are Oak, Poplar, Beech, Elm, Cypress, Firr; but some of them are not so proper for Building as others.