An Abridgment of the Architecture of Vitruvius Part 3

For to make the right use of Sand, you must first consider what it is to be employ'd in; for if it be Mortar for Plastring, you must not make use of Sand that was lately dug out, for it drys the Mortar too fast, which cracks the Plastring; but quite contrary if it be to be employ'd in Masonry, it must not have been a long time expos'd to the Air, for the Sun and the Moon do so alter it, that the Rain dissolves it, and turns it almost all into Earth.

[Sidenote: _Lib. 2. Chap. 5._]

The Proportion that Sand and Lime ought to have to make good Mortar, should be three parts of Sand that is dug, or two parts of River-Sand or Sea-Sand against one of Lime, and 'twill be yet much better, if you add to the Sand of the Sea and the River a third part of Tiles well beaten.

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

One of the Princ.i.p.al Things that is to be observ'd in making Mortar, is, to mix it well. The Grecian Workmen were so careful of this, that they Tewed it a great while, putting Ten Men to every Vessel wherein they wrought it, which gave so great a hardness to the Mortar, that when any big pieces of Plaster fell off the Old Walls, they made Tables of it.

ART. III.

_Of the Foundation._

[Sidenote: _Lib. 6. Chap. 11._]

The Foundation is the most important part of the Fabrick; for the Faults committed in it cannot be so easily remedied as in other parts.

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

To lay the Foundation well, you must dig till you come to solid Ground, and even into the solid as much as is necessary to support the Weight of the Walls; it must be larger below than above the Superficies of the Earth.

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

When you have found firm Earth to make it more solid, you must beat it with a Rammer; but if you cannot arrive at solid Earth, but find it still soft and spungy, you must dig as far as you can, and drive in Piles of Alder, Olive, or Oak, a little singed, near together, and fill up the void Places between the Piles with Coal.

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

In short, you must make all Masonry with the most solid Stone that can be found for this use.

To make the Binding of the Stones the stronger in the Foundation of great Fabricks, you must put Piles of Olive a little singed and placed very thick from one Parement or Course to another, which serves, as it were, for Keys and Braces; for this Wood so prepar'd, is not subject to Worms, and will endure for ever, either in the Earth or in the Water, without the least Damage.

[Sidenote: _Lib. 6. Chap. 11._]

When you would make Cellars, the Foundations must be much larger; for the Wall that is to support the Earth requires a greater thickness to resist the strong Efforts that the Earth makes against it in Winter, at which time it swells and becomes more heavy by reason of the Water it has drunk up.

ART. IV.

_Of the Walls._

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

The right ordering of Stones joined with Mortar, which is call'd Masonry, is sevenfold; there are three of them which are of hewed Stone; _viz._ that which is in Form of a _Net_, that which is in _Binding_, that which is call'd the _Greek Masonry_. There are likewise three sorts of Masonry of unhewed Stones; _viz._ that which is of an _equal Course_; and that which is of an unequal, and that which is fill'd up in the middle; the seventh is compounded of all the rest.

The _Net-Masonry_ is that which is made of Stones perfectly squar'd in their Courses, and are laid so, that the Joints go obliquely, and the Diagonals are the one Perpendicular, and the other Level. This is the most pleasing Masonry to the Sight, but it is apt to crack. See the Figure A. Table I.

The Masonry call'd the _Bound-Masonry_, is that, as _Vitruvius_ explains it, in which the Stones are plac'd one upon another like Tiles; that is to say, where the Joints of the Beds are Level, and the Mounters are Perpendicular; so that the Joint that mounts and separates two Stones falls directly upon the middle of the Stone which is below.

Some Authors call this sort of Masonry _Incertain_, but they are mistaken; for they read _Incerta_ instead of_Inserta_; it is not so Beautiful as the Net-work, but it is more solid and durable. See the Figure BB. Table I.

The Masonry which _Vitruvius_ says is particular to the _Greeks_, is that, where after we have laid two Stones, each of which make a Parement or _Course_, another is laid at the end, which makes two Parements or _Courses_, and all the Building through observe this Order. This may be call'd _Double-Binding_; for the Binding is not only of Stones of the same _Course_ one with another, but likewise of one _Course_ with another _Course_. See Figure CC. Table I.

The manner of Walling by unequal Courses call'd _Isodomum_ by the Ancients, differs in nothing from the Masonry call'd _Bound-Masonry_, but only in this, that the Stones are not hewed. See Figure D. Table I.

The other manner by unequal Courses call'd _Pseudisodomum_ is also made of unhewed Stone, and laid in _Bound-Work_, but they are not of the same thickness, and there is no equality observ'd, but only in the several Courses, the Courses themselves being unequal one to another. See Figure A. Table I.

The Masonry which is fill'd up in the middle, call'd by the Ancients _Emplecton_, is likewise made of unhewed Stone and by Courses, but the Stones are only set in order as to the _Parements_ or _Courses_, but the middle is fill'd up with Stones thrown in carelesly among the Mortar.

See Fig. FF, GG, H. Table I.

Among all these sorts of Masonry, that will always be best which is made of Stones of an indifferent size, rather lesser than greater; to the end that the Mortar penetrating them in more parts may bind them faster, and the strength of the Mortar does not so soon decay. For we see that the Mortar which is laid in the Joints or Seams of the greater Stones with time decays and turns to Dust, which never happens to the most Ancient Fabricks which have been built of little Stones. From thence we may conclude, that it is ill Husbandry to be sparing of Mortar.

For this reason _Vitruvius_ proposes another sort of Masonry, which may be call'd the _Compound Masonry_, for it is all the former together, of Stones hewed and unhewed, and fastned together with Cramp-Irons. The Structure is as follows: The _Courses_ being made of hew'd Stone, the middle place which was left void is fill'd up with Mortar and Pebbles thrown in together; after this they bind the Stones of one _Parement_ or _Course_ to those of another with Cramp-Irons fasten'd with melted Lead. This is done to the end, that the abundance of Mortar which is in the middle may furnish and communicate a sufficient Humidity to the Joints of the great Stones which make the _Parements_. See the Figure K.

Table I.

There are many Precautions to be given to make the Masonry more firm and durable, and these Precautions are common to all the different sorts of Masonry.

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

When you would have the Walls very thick, for great and heavy Buildings, you must strengthen the inner part of the Wall with long Piles of singed Olive, which serves for Keys and Braces, for this Wood being so prepar'd never corrupts.

[Sidenote: _Lib. 6. Chap. 11._]

[Sidenote: _Vide Index._]

It is likewise of great Importance for the strength of Walls, that all be directly Perpendicular, and that the _Chains_, the _Pillars_ and _Pieds-droits_ or _Piers_ be so situated, that _solid_ always answer'd to the _solid_; for if there be any part of the Wall or any Pillar that carrys false, it is impossible the Work should continue long.

There are also two ways of strengthning the Walls, which are either to ease them of their own weight, or of that of the Earth which they are to support.

The first way of easing is in those Places where there are void s.p.a.ces, as above Doors or Windows. These eas.e.m.e.nts may be made two different ways; the first is to put over the Lintel which supports the Wall, which is over the void s.p.a.ce of the Gates and Windows, two Beams, which lying or resting below directly upon _Pieds-droits_ or _Piers_ meet together above.

The other way is, to make directly over the void s.p.a.ces Vaulted Arches with Stones cut corner-ways and tending to one Center. For the Walls be so strengthned by the means of these eas.e.m.e.nts, that part of the Wall which is below will not sink at all being easied of the load of the part that is above, and if some defect should happen by tract of time, it may be mended without propping that which is above.

The second way of easing, is, for Walls that are made to support the Earth; for, besides the extraordinary thickness which they ought to have, they should have likewise b.u.t.tresses on that side next the Earth, so far distant one from another as is the breadth of the Wall; they ought likewise to have an _Emparement_ or large Foundation which must be equal to the height of the Wall, so that they go diminishing by degrees from the bottom to the top, where they come to equal the height of the Wall.

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

The effect of these _b.u.t.tresses_ is not only to support the Earth by their Resistance, but likewise to lessen its Efforts when it swells, in dividing it into many parts.

[Sidenote: _Lib. 6. Chap. 11._]

And if it be judg'd that these _b.u.t.tresses_ be not sufficient, the Wall also which supports the Earth must be strengthned with other _b.u.t.tresses_ within.

ART. V.

_Of Flooring and Ceiling._

There are four sorts of Flooring, some are upon the _Superficies_ of the Ground, others between two Stories, others make the Roof of the House in Plat-form, and the last is _Plat-Fond_.