_Of the Choice of Materials._
The 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.
The Firr, because it has great plenty of Air, and Fire, and but little
Earth and Water, is light, and does not easily bend; but is very subject
to Worms and Fire.
The Oak which is more Earthy lasts for ever under Ground; but above
Ground is apt to cleave.
The Beech which has little of Earthiness, Humidity and Fire, but great
plenty of Air, is not very solid and easily breaks.
The Poplar and the Linden Trees are only good for light Work, they are
easily cut and so finest for Carving.
The Alder is good to make Piles of in Marshy Places.
The Elm and the Ash have this property, that they do not easily cleave,
and that they are pliable.
The Yoke-Elm is likewise pliable, and yet very strong; this is the
Reason that they made Yokes for their Oxen of them in Old Time.
The Pine and the Cypress have this defect, that they easily bend under
any Weight, because of their great Humidity; but they have this
Advantage, that their Humidity does not engender Worms, because of their
Bitterness which kills them.
The Juniper and the Cedar have the same Vertue of hindering Corruption:
the Juniper by its Gum, which is call'd _Sandarax_, and the Cedar by its
Oil call'd _Cedrium_.
The Larch-Tree has likewise the same Vertue, but its particular property
is, that it will not burn. There is a remarkable Story of this Wood,
which is, That when _Julius Caesar_ besieg'd a Castle at the Foot of the
_Alpes_, there was a Tower built of this Wood, which prov'd the
Principal Defence of the Place. He thought to take it easily by making
a great Fire at the Foot of the Tower, but for all this great Fire, the
Tower did not suffer the least Damage.
The Olive-Tree is likewise very serviceable, if it be put in the
Foundations, and Walls of Cities; for after it has been singed a little,
and interlaced among the Stones, it lasts for ever, and is out of all
danger of Corruption.
Lime is made of White Stones or Flinty Pebbles, the harder the Stones
are which 'tis made of, the better it is for Building. That which is
made of soft Spongy Stones, is proper for Plastring.
There are five sorts of Sand; _viz._ Sand that is dug out of the Ground,
River Sand, Gravel, Sea-Sand, and Pozzolana, which is a Sand peculiar to
some Parts of _Italy_.
The best Sand is that which being rubb'd between the Hands makes a
little Noise, which that Sand does not, which is Earthy, because it is
not rough. Another Mark of good Sand is, that when 'tis put upon any
Thing that is White and shak'd off, it leaves no Mark behind.
The Sand which is dug out of the Earth has all these Qualities, and is
esteem'd the best. _Vitruvius_ makes four sorts of it; _viz._ White,
Black, Red, and Bright like a Carbuncle.
If it happen that there be no good Place to dig Sand in, we may make use
of Sea-Sand, or River-Sand, which is likewise better for Plastering than
the Sand which is digged, which is excellent for Building, because it
drys quickly. Gravel likewise is very good, provided the grosser Parts
be taken away. Sea-Sand is worst of all, because 'tis long adrying; and
for this Reason, where 'tis made use of in Building, they are forc'd to
desist sometimes till it dry.
The Sand which is found near _Naples_ call'd _Pozzolana_ is so proper to
make good Mortar, if it be mixed with Lime, that not only in the
ordinary Fabricks, but even in the very bottom of the Sea it grows into
a wonderful hard Body. In Old Times they made use of it for Moles or
Ports of the Sea, for after having made with Piles and Boards a
Partition, they fill'd up the whole Compass of the Partition with this
Mortar, which dry'd of it self in the middle of the Water and became a
solid Body.