The Ten Books on Architecture, 2.8

Vitruvius  translated by Joseph Gwilt

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Of the Different Kinds of Walls

8The different species of walls are, the RETICULATUM (net-like), a method now in general use, and the INCERTUM (uncertain), which is the antient mode. The reticulatum is the most beautiful, but is very liable to split, from the beds of the stones being unstable, and its deficiency in respect of bond. The incertum, on the contrary, course over course, and the whole bonded together, does not present so beautiful an appearance, though stronger than the reticulatum.

2Both species should be built of the smallest sized stones, that the walls, by sucking up, and attaching themselves to, the mortar, may last the longer. For as the stones are of a soft and porous nature, they absorb, in drying, the moisture of the mortar, and this, if used plentifully, will consequently exercise a greater cementing power; because from their containing a larger portion of moisture, the wall will not, of course, dry so soon as otherwise; and as soon as the moisture is absorbed by the pores of the stone from the mortar, the lime, losing its power, leaves the sand, so that the stones no longer adhere to it, and in a short time the work becomes unsound.

3We may see this in several monuments about the city, which have been built of marble or of stones squared externally; that is, on the face, but filled up with rubble run with mortar. Time, in these, has taken up the moisture of the mortar, and destroyed its efficacy, by the porosity of the surface on which it acted. All cohesion is thus ruined, and the walls fall to decay.

4He who is desirous that this may not happen to his work, should build his two face walls two feet thick either of red stone or of brick or common flint, binding them together with iron cramps run with lead, and duly preserving the middle space or cavity. The materials, in this case, not being thrown in at random, but the work well brought up on the beds, the upright joints properly arranged, and the face walls, moreover, regularly tied together, they are not liable to bulge, nor be otherwise disfigured.

5In these respects one cannot refrain from admiring the walls of the Greeks. They make no use of soft stone in their buildings: when, however, they do not employ squared stone, they use either flint or hard stone; and, as though building with brick, they cross or break the upright joints, and thus produce the most durable work. There are two sorts of this species of work; one called ISODOMUM, the other PSEUDISODOMUM.

6The first is so called, because in it all the courses are of an equal height; the latter received its name from the unequal heights of the courses. Both these methods make sound work: first, because the stones are hard and solid, and therefore unable to absorb the moisture of the mortar, which is thus preserved to the longest period; secondly, because the beds being smooth and level, the mortar does not escape; and the wall moreover, bonded throughout its whole thickness, becomes eternal.

7There is still another method, which is called ἔμπλεκτον (EMPLECTUM), in use even among our country workmen. In this species the faces are wrought. The other stones are, without working, deposited in the cavity between the two faces, and bedded in mortar as the wall is carried up. But the workmen, for the sake of despatch, carry up these casing walls, and then tumble in the rubble between them; so that there are thus three distinct thicknesses; namely, the two sides or facings, and the filling in. The Greeks, however, pursue a different course, laying the stones flat, and breaking the vertical joints; neither do they fill in the middle at random, but, by means of bond stones, make the wall solid, and of one thickness or piece. They moreover cross the wall, from one face to the other, with bond stones of a single piece, which they call διατόνοι, (DIATONI) tending greatly to strengthen the work.

8He, therefore, who is desirous of producing a lasting structure, is enabled, by what I have laid down, to choose the sort of wall that will suit his purpose. Those walls which are built of soft and smooth-looking stone, will not last long. Hence, when valuations are made of external walls, we must not put them at their original cost; but having found, from the register, the number of lettings they have gone through, we must deduct for every year of their age an eightieth part of such cost, and set down the remainder or balance as their value, inasmuch as they are not calculated to last more than eighty years.

9This is not the practice in the case of brick walls, which, whilst they stand upright, are always valued at their first cost. Hence, in some states, not only public and private buildings, but even royal structures, are built of brick. We may instance that part of the wall at Athens towards Mounts Hymettus and Pentelicus, the temples of Jupiter and Hercules, in which the cells are of brick, whilst the columns and their entablatures are of stone, in Italy the antient and exquisitely wrought wall of Arezzo, and at Tralles a palace for the Attalic kings, which is the official residence of the priest. Some pictures painted on brick walls at Sparta, after being cut out, were packed up in wooden cases and transported to the Comitium to grace the Ædileship of Varro and Murena.

10In the house of Croesus, which the Sardians call Gerusia, established for the repose and comfort of the citizens in their old age, as also in the house of Mausolus, a very powerful king of Halicarnassus, though all the ornaments are of Proconnesian marble, the walls are of brick, are remarkably sound at the present day, and the plastering with which they are covered is so polished that they sparkle like glass. The prince who caused them to be thus built was not, however, restrained by economy; for, as king of Caria, he must have been exceedingly rich.

11Neither could it be urged that it was from want of skill and taste in architecture, that he did so. Born at Mylasa, and perceiving that Halicarnassus was a situation fortified by nature, and a place well adapted for commerce, with a commodious harbour, he fixed his residence there. The site of the city bears a resemblance to a theatre, as to general form. In the lowest part of it, near the harbour, a forum was built: up the hill, about the middle of the curve, was a large square in the centre of which stood the mausoleum, a work of such grandeur that it was accounted one of the seven wonders of the world. In the centre, on the summit of the hill, was the temple of Mars, with its colossal statue, which is called ἀκρόλιθος, sculptured by the eminent hand of Leocharis. Some, however, attribute this statue to Leocharis; others to Timotheus. On the right, at the extreme point of the curve, was the temple of Venus and Mercury, close to the fountain of Salmacis.

12It is a vulgar error, that those who happen to drink thereat are affected with love-sickness. As, however, this error is general, it will not be amiss to correct the impression. It is not only impossible that the water should have the effect of rendering men effeminate and unchaste; but, on the contrary, that alluded to is clear as crystal, and of the finest flavour. The origin of the story, by which it gained the reputation of the above quality, is as follows. When Melas and Arevanias brought to the place a colony from Argos and Trœzene, they drove out the barbarous Carians and Lelegæ. These, betaking themselves to the mountains in bodies, committed great depredations, and laid waste the neighbourhood. Some time afterwards, one of the colonists, for the sake of the profit likely to arise from it, established close to the fountain, on account of the excellence of its water, a store where he kept all sorts of merchandize; and thus it became a place of great resort of the barbarians who were drawn thither. Coming, at first, in small, and at last in large, numbers, the barbarians by degrees shook off their savage and uncivilized habits, and changed them, without coercion for those of the Greeks. The fame, therefore, of this fountain, was acquired, not by the effeminacy which it is reputed to impart, but by its being the means through which the minds of the barbarians were civilized.

13I must now, however, proceed to finish my description of the city. On the right summit we have described the temple of Venus and the above named fountain to have been placed: on the left stood the royal palace, which was planned by Mausolus himself. This commanded, on the right, a view of the forum and harbour, and of the whole circuit of the walls: on the left, it overlooked a secret harbour, hidden by the mountains, into which no one could pry, so as to be aware of what was transacting therein. In short, from his palace, the king, without any person being aware of it, could give the necessary orders to his soldiers and sailors.

14After the death of Mausolus, the Rhodians, indignant at his wife, who succeeded to the government, governing the whole of Caria, fitted out a fleet, for the purpose of seizing the kingdom. When the news reached Artemisia, she commanded her fleet to lie still in the secret harbour; and having concealed the sailors and mustered the marines, ordered the rest of the citizens to the walls. When the well appointed squadron of the Rhodians should enter the large harbour, she gave orders that those stationed on the walls should greet them, and promise to deliver up the town. The Rhodians, leaving their ships, penetrated into the town; at which period Artemisia, by the sudden opening of a canal, brought her fleet round, through the open sea, into the large harbour; whence the Rhodian fleet, abandoned by its sailors and marines, was easily carried out to sea. The Rhodians, having now no place of shelter, were surrounded in the forum and slain.

15Artemisia then embarking her own sailors and marines on board of the Rhodian fleet, set sail for Rhodes. The inhabitants of that city seeing their vessels return decorated with laurels, thought their fellow citizens were returning victorious, and received their enemies. Artemisia having thus taken Rhodes, and slain the principal persons of the city, raised therein a trophy of her victory. It consisted of two brazen statues, one of which represented the state of Rhodes, the other was a statue of herself imposing a mark of infamy on the city. As it was contrary to the precepts of the religion of the Rhodians to remove a trophy, they encircled the latter with a building, and covered it after the custom of the Greeks, giving it the name ἄβατον.

16If therefore, kings of such great power did not despise brick buildings, those who, from their great revenue and spoils in war, can afford the expence not only of squared and rough stone, but even of marble buildings, must not despise brick structures when well executed. I shall now explain why this species of walls is not permitted in the city of Rome, and also why such walls ought not to be permitted.

17The public laws forbid a greater thickness than one foot and a half to be given to walls that abut on a public way, and the other walls, to prevent loss of room, are not built thicker. Now brick walls, unless of the thickness of two or three bricks, at all events of at least one foot and a half, are not fit to carry more than one floor, so that from the great population of the city innumerable houses would be required. Since, therefore, the area it occupies would not in such case contain the number to be accommodated, it became absolutely necessary to gain in height that which could not be obtained on the plan. Thus by means of stone piers or walls of burnt bricks or unsquared stones, which were tied together by the timbers of the several floors, they obtained in the upper story excellent dining rooms. The Roman people by thus multiplying the number of stories in their houses are commodiously lodged.

18Having explained why, on account of the narrowness of the streets in Rome, walls of brick are not allowed in the city, I shall now give instructions for their use out of the city when required, to the end that they may be durable. On the top of a wall immediately under the roof, there should be a course of burnt bricks, about one foot and a half in height, and projecting over the walls like the corona of a cornice; thus the injury to be guarded against in such a wall, will be prevented; for if any tiles should be accidentally broken or dislodged by the wind, so as to afford a passage for the rain, the burnt brick, a protection to it, will secure the wall itself from damage, and the projection will cause the dropping of the water to fall beyond the face of the wall and thus preserve it.

19To judge of such burnt bricks as are fit for the purpose is not at first an easy matter; the only way of ascertaining their goodness is to try them through a summer and winter, and, if they bear out through these undamaged, they may be used. Those which are not made of good clay are soon injured by the frost and rain; hence if unfit to be used in roofs they will be more unfit in walls. Walls built of old tiles are consequently very lasting.

20As to wattled walls, would they had never been invented, for though convenient and expeditiously made, they are conducive to great calamity from their acting almost like torches in case of fire. It is much better, therefore, in the first instance, to be at the expense of burnt bricks, than from parsimony to be in perpetual risk. Walls moreover, of this sort, that are covered with plaster are always full of cracks, arising from the crossing of the laths; for when the plastering is laid on wet, it swells the wood, which contracts as the work dries, breaking the plastering. But if expedition, or want of funds, drives us to the use of this sort of work, or as an expedient to bring work to a square form, let it be executed as follows. The surface of the foundation whereon it is to stand must be somewhat raised from the ground or pavement. Should it ever be placed below them it will rot, settle, and bend forward, whereby the face of the plastering will be injured. I have already treated on walls, and generally on the mode of preparing and selecting the materials for them. I shall now proceed to the use of timber in framing, and to a description of its several sorts, as also of the mode of fitting timbers together, so that they may be as durable as their nature will permit.

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