Oeconomy teaches the Architect to have regard to the Expences that are to be made, and to the Quality of the Materials, near the Places where he Builds, and to take his Measures rightly for the Order and Disposition; _viz._ to give the Fabrick a convenient Form and Magnitude.

These Eight Parts, as we have said, have a Relation to the Three first, _viz._ _Solidity_, _Convenience_, _Beauty_, which suppose, _Order, Disposition_, _Proportion_, _Decorum_ and _Oeconomy_. This is the reason that we divide this first Part only into Three Chapters; the first is of the Solidity; the second of the Convenience; the third of the Beauty of the Fabrick.

CHAP. II.

_Of the Solidity of Buildings._

ARTICLE I.

_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 Princ.i.p.al 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 Part.i.tion, they fill'd up the whole Compa.s.s of the Part.i.tion with this Mortar, which dry'd of it self in the middle of the Water and became a solid Body.

ART. II.

_Of the Use of the Materials._

The first thing we should have a Care of before we begin to build, is, to have the Stones dug out of the Quarry before they be used, and to expose them in some open Place, to the end that those which are endamaged by the Air, during this Time, may be put in the Foundation, and those that prove Durable and Good may be kept for the Walls above Ground.

We must likewise have a great care of the Wood which we make use of; That it be cut in a seasonable Time, which is in Autumn and Winter; for then it is not full of that superfluous Humidity which weakened it in dilating its Fibers, but it is firm and well closed by the Cold. This is so true, that the Wood of Trees which grow and become very great in a little Time, by reason of their great Humidity, is tender and apt to break, and very unfit for Building. Which Experience shows us particularly in those Firrs call'd _Supernates_, which grow in _Italy_, on that side the _Apennine_, towards the _Adriatick_-Sea, for they are great and beautiful, but their Wood is not good for Building; whereas those on the other side of the Mountain, which are exposed to Heat and Dryness, call'd _Infernates_, are very good for Building.

This superfluous Humidity endamages Trees so much, that we are sometimes constrain'd to make a hole at the foot of the Tree and let it run out, which is the occasion of the Practice which is observ'd in cutting of Wood for Building, to Tap that Tree at the Foot, cutting not only the Bark, but even some part of the Wood it self, and so leave it for some time before it be Fell'd.

[Sidenote: _Lib. 1. Chap. 5._]

It is likewise easie to judge of what great Importance the draining of this superfluous Humidity is for strengthning the Timber, and hindring Corruption, from this, That those Piles which are interlaced among the Stones in the Walls and Fortifications of Towns endure for ever without Corrupting, when they have been burnt a little on the outside.

[Sidenote: _Lib. 1. Chap. 11._]

[Sidenote: _Lib. 2. Chap. 8._]

Bricks ought not to be made use of but in very thick Walls; for this reason they did not build with Brick in _Rome_, for to save Ground; they were not permitted to make the Walls of their Houses above a Foot and a Half thick, which Makes about 16 Inches and a half of our Foot.

They likewise never made the top of their Walls with Brick; for the Brick of the Ancients not being baked, this part of the Wall would have been easily endamaged; for this reason they built it with Tiles, a foot and a half high, comprizing the Cornish or Entablature which was made likewise of Tiles to cast off the Water and defend the rest of the Wall.

They likewise chose for these Cornishes the best Tiles, _viz._ those that had been long on the top of the Houses, and given sufficient Proof that they were well baked and made of good Matter.

The Walling with Brick was so much esteem'd among the Ancients, that all their Fabricks, as well publick as private, and their most beautiful Palaces were built with them. But that which princ.i.p.ally made this sort of Building be esteem'd, was its great Duration; for when expert Architects were called to make an Estimate of Buildings, they always deducted an 80th. part of what they judged the Building cost for every Year that the Wall had been standing, for they supposed that the Walls could not ordinarily endure more than Fourscore Years; but when they valued Buildings of Brick, they always valued them at what they cost at first, supposing them to be of an Eternal Duration.

To make the right use of Lime and Sand, and to make good Mortar of them, it is necessary that the Lime be first well Quench'd, and that it be kept a long time, to the end that if there be any Piece of it that is not well burnt in the Kiln, it may, being extinguished at leasure, soften as well as the rest. This is of Great Importance particularly in Plastering and Works of _Stuck_, which is a Composition of Marble finely beaten with Lime. For if any little Pieces remain that are not well baked, when they come to be made use of, they crack and break the Work.

[Sidenote: _Lib. 7. Chap. 3._]

The way to know whether the Lime be well Quench'd, is thus: You may thrust a Chip of Wood into it or a Knife, and if the Chip of Wood meet with any Stones, or that the Knife comes out clean without any sticking to it, it signifies the Lime was not will burnt; for when 'tis well Quench'd, it is Fat and will stick to the Knife; but the quite contrary happens to Mortar, for it is neither well prepar'd, nor well mix'd, if it stick to the Trowel.

[Sidenote: _Lib. 2. Chap. 4._]