Ten Books on Architecture

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2. All these soft kinds have the advantage that they can be easily
worked as soon as they have been taken from the quarries. Under cover
they play their part well; but in open and exposed situations the frost
and rime make them crumble, and they go to pieces. On the seacoast, too,
the salt eats away and dissolves them, nor can they stand great heat
either. But travertine and all stone of that class can stand injury
whether from a heavy load laid upon it or from the weather; exposure to
fire, however, it cannot bear, but splits and cracks to pieces at once.
This is because in its natural composition there is but little moisture
and not much of the earthy, but a great deal of air and of fire.
Therefore, it is not only without the earthy and watery elements, but
when fire, expelling the air from it by the operation and force of heat,
penetrates into its inmost parts and occupies the empty spaces of the
fissures, there comes a great glow and the stone is made to burn as
fiercely as do the particles of fire itself.

3. There are also several quarries called Anician in the territory of
Tarquinii, the stone being of the colour of peperino. The principal
workshops lie round the lake of Bolsena and in the prefecture of
Statonia. This stone has innumerable good qualities. Neither the season
of frost nor exposure to fire can harm it, but it remains solid and
lasts to a great age, because there is only a little air and fire in its
natural composition, a moderate amount of moisture, and a great deal of
the earthy. Hence its structure is of close texture and solid, and so it
cannot be injured by the weather or by the force of fire.

4. This may best be seen from monuments in the neighbourhood of the town
of Ferento which are made of stone from these quarries. Among them are
large statues exceedingly well made, images of smaller size, and flowers
and acanthus leaves gracefully carved. Old as these are, they look as
fresh as if they were only just finished. Bronze workers, also, make
moulds for the casting of bronze out of stone from these quarries, and
find it very useful in bronze-founding. If the quarries were only near
Rome, all our buildings might well be constructed from the products of
these workshops.

5. But since, on account of the proximity of the stone-quarries of
Grotta Rossa, Palla, and the others that are nearest to the city,
necessity drives us to make use of their products, we must proceed as
follows, if we wish our work to be finished without flaws. Let the stone
be taken from the quarry two years before building is to begin, and not
in winter but in summer. Then let it lie exposed in an open place. Such
stone as has been damaged by the two years of exposure should be used in
the foundations. The rest, which remains unhurt, has passed the test of
nature and will endure in those parts of the building which are above
ground. This precaution should be observed, not only with dimension
stone, but also with the rubble which is to be used in walls.

[Illustration: Photo. Moscioni

EXAMPLE OF OPUS INCERTUM. THE CIRCULAR TEMPLE AT TIVOLI]

CHAPTER VIII

METHODS OF BUILDING WALLS

1. There are two styles of walls: "opus reticulatum," now used by
everybody, and the ancient style called "opus incertum." Of these, the
reticulatum looks better, but its construction makes it likely to crack,
because its beds and builds spread out in every direction. On the other
hand, in the opus incertum, the rubble, lying in courses and imbricated,
makes a wall which, though not beautiful, is stronger than the
reticulatum.

2. Both kinds should be constructed of the smallest stones, so that the
walls, being thoroughly puddled with the mortar, which is made of lime
and sand, may hold together longer. Since the stones used are soft and
porous, they are apt to suck the moisture out of the mortar and so to
dry it up. But when there is abundance of lime and sand, the wall,
containing more moisture, will not soon lose its strength, for they will
hold it together. But as soon as the moisture is sucked out of the
mortar by the porous rubble, and the lime and sand separate and
disunite, the rubble can no longer adhere to them and the wall will in
time become a ruin.

3. This we may learn from several monuments in the environs of the city,
which are built of marble or dimension stone, but on the inside packed
with masonry between the outer walls. In the course of time, the mortar
has lost its strength, which has been sucked out of it by the porousness
of the rubble; and so the monuments are tumbling down and going to
pieces, with their joints loosened by the settling of the material that
bound them together.

4. He who wishes to avoid such a disaster should leave a cavity behind
the facings, and on the inside build walls two feet thick, made of red
dimension stone or burnt brick or lava in courses, and then bind them to
the fronts by means of iron clamps and lead. For thus his work, being no
mere heap of material but regularly laid in courses, will be strong
enough to last forever without a flaw, because the beds and builds, all
settling equally and bonded at the joints, will not let the work bulge
out, nor allow the fall of the face walls which have been tightly
fastened together.

5. Consequently, the method of construction employed by the Greeks is
not to be despised. They do not use a structure of soft rubble polished
on the outside, but whenever they forsake dimension stone, they lay
courses of lava or of some hard stone, and, as though building with
brick, they bind the upright joints by interchanging the direction of
the stones as they lie in the courses. Thus they attain to a perfection
that will endure to eternity. These structures are of two kinds. One of
them is called "isodomum," the other "pseudisodomum."

6. A wall is called isodomum when all the courses are of equal height;
pseudisodomum, when the rows of courses do not match but run unequally.
Both kinds are strong: first, because the rubble itself is of close
texture and solid, unable to suck the moisture out of the mortar, but
keeping it in its moist condition for a very long period; secondly,
because the beds of the stones, being laid smooth and level to begin
with, keep the mortar from falling, and, as they are bonded throughout
the entire thickness of the wall, they hold together for a very long
period.

7. Another method is that which they call [Greek: emplekton], used also
among us in the country. In this the facings are finished, but the other
stones left in their natural state and then laid with alternate bonding
stones. But our workmen, in their hurry to finish, devote themselves
only to the facings of the walls, setting them upright but filling the
space between with a lot of broken stones and mortar thrown in anyhow.
This makes three different sections in the same structure; two
consisting of facing and one of filling between them. The Greeks,
however, do not build so; but laying their stones level and building
every other stone length-wise into the thickness, they do not fill the
space between, but construct the thickness of their walls in one solid
and unbroken mass from the facings to the interior. Further, at
intervals they lay single stones which run through the entire
thickness of the wall. These stones, which show at each end, are called
[Greek: diatonoi], and by their bonding powers they add very greatly to
the solidity of the walls.

[Illustration: Photo. Moscioni

OPUS RETICULATUM FROM THE THERMAE OF HADRIAN'S VILLA AT TIVOLI]

[Illustration: Photo. Moscioni

EXAMPLE OF OPUS RETICULATUM FROM THE DOORWAY OF THE STOA POECILE. VILLA
OF HADRIAN AT TIVOLI]

8. One who in accordance with these notes will take pains in selecting
his method of construction, may count upon having something that will
last. No walls made of rubble and finished with delicate beauty--no such
walls can escape ruin as time goes on. Hence, when arbitrators are
chosen to set a valuation on party walls, they do not value them at what
they cost to build, but look up the written contract in each case and
then, after deducting from the cost one eightieth for each year that the
wall has been standing, decide that the remainder is the sum to be paid.
They thus in effect pronounce that such walls cannot last more than
eighty years.

9. In the case of brick walls, however, no deduction is made provided
that they are still standing plumb, but they are always valued at what
they cost to build. Hence in some states we may see public buildings and
private houses, as well as those of kings, built of brick: in Athens,
for example, the part of the wall which faces Mt. Hymettus and
Pentelicus; at Patras, the cellae of the temple of Jupiter and Hercules,
which are brick, although on the outside the entablature and columns of
the temple are of stone; in Italy, at Arezzo, an ancient wall
excellently built; at Tralles, the house built for the kings of the
dynasty of Attalus, which is now always granted to the man who holds the
state priesthood. In Sparta, paintings have been taken out of certain
walls by cutting through the bricks, then have been placed in wooden
frames, and so brought to the Comitium to adorn the aedileship of Varro
and Murena.

10. Then there is the house of Croesus which the people of Sardis have
set apart as a place of repose for their fellow-citizens in the
retirement of age,--a "Gerousia" for the guild of the elder men. At
Halicarnassus, the house of that most potent king Mausolus, though
decorated throughout with Proconnesian marble, has walls built of brick
which are to this day of extraordinary strength, and are covered with
stucco so highly polished that they seem to be as glistening as glass.
That king did not use brick from poverty; for he was choke-full of
revenues, being ruler of all Caria.

11. As for his skill and ingenuity as a builder, they may be seen from
what follows. He was born at Melassa, but recognizing the natural
advantages of Halicarnassus as a fortress, and seeing that it was
suitable as a trading centre and that it had a good harbour, he fixed
his residence there. The place had a curvature like that of the seats in
a theatre. On the lowest tier, along the harbour, was built the forum.
About halfway up the curving slope, at the point where the curved
cross-aisle is in a theatre, a broad wide street was laid out, in the
middle of which was built the Mausoleum, a work so remarkable that it is
classed among the Seven Wonders of the World. At the top of the hill, in
the centre, is the fane of Mars, containing a colossal acrolithic statue
by the famous hand of Leochares. That is, some think that this statue is
by Leochares, others by Timotheus. At the extreme right of the summit is
the fane of Venus and Mercury, close to the spring of Salmacis.

12. There is a mistaken idea that this spring infects those who drink of
it with an unnatural lewdness. It will not be out of place to explain
how this idea came to spread throughout the world from a mistake in the
telling of the tale. It cannot be that the water makes men effeminate
and unchaste, as it is said to do; for the spring is of remarkable
clearness and excellent in flavour. The fact is that when Melas and
Arevanias came there from Argos and Troezen and founded a colony
together, they drove out the Carians and Lelegans who were barbarians.
These took refuge in the mountains, and, uniting there, used to make
raids, plundering the Greeks and laying their country waste in a cruel
manner. Later, one of the colonists, to make money, set up a
well-stocked shop, near the spring because the water was so good, and
the way in which he carried it on attracted the barbarians. So they
began to come down, one at a time, and to meet with society, and thus
they were brought back of their own accord, giving up their rough and
savage ways for the delights of Greek customs. Hence this water acquired
its peculiar reputation, not because it really induced unchastity, but
because those barbarians were softened by the charm of civilization.

[Illustration: THE MAUSOLEUM AT HALICARNASSUS AS RESTORED BY FRIEDRICH
ADLER]

13. But since I have been tempted into giving a description of this
fortified place, it remains to finish my account of it. Corresponding to
the fane of Venus and the spring described above, which are on the
right, we have on the extreme left the royal palace which king Mausolus
built there in accordance with a plan all his own. To the right it
commands a view of the forum, the harbour, and the entire line of
fortifications, while just below it, to the left, there is a concealed
harbour, hidden under the walls in such a way that nobody could see or
know what was going on in it. Only the king himself could, in case of
need, give orders from his own palace to the oarsmen and soldiers,
without the knowledge of anybody else.

14. After the death of Mausolus, his wife Artemisia became queen, and
the Rhodians, regarding it as an outrage that a woman should be ruler of
the states of all Caria, fitted out a fleet and sallied forth to seize
upon the kingdom. When news of this reached Artemisia, she gave orders
that her fleet should be hidden away in that harbour with oarsmen and
marines mustered and concealed, but that the rest of the citizens should
take their places on the city wall. After the Rhodians had landed at the
larger harbour with their well-equipped fleet, she ordered the people on
the wall to cheer them and to promise that they would deliver up the
town. Then, when they had passed inside the wall, leaving their fleet
empty, Artemisia suddenly made a canal which led to the sea, brought her
fleet thus out of the smaller harbour, and so sailed into the larger.
Disembarking her soldiers, she towed the empty fleet of the Rhodians out
to sea. So the Rhodians were surrounded without means of retreat, and
were slain in the very forum.

15. So Artemisia embarked her own soldiers and oarsmen in the ships of
the Rhodians and set forth for Rhodes. The Rhodians, beholding their own
ships approaching wreathed with laurel, supposed that their
fellow-citizens were returning victorious, and admitted the enemy. Then
Artemisia, after taking Rhodes and killing its leading men, put up in
the city of Rhodes a trophy of her victory, including two bronze
statues, one representing the state of the Rhodians, the other herself.
Herself she fashioned in the act of branding the state of the Rhodians.
In later times the Rhodians, labouring under the religious scruple which
makes it a sin to remove trophies once they are dedicated, constructed a
building to surround the place, and thus by the erection of the "Grecian
Station" covered it so that nobody could see it, and ordered that the
building be called "[Greek: abaton]."

16. Since such very powerful kings have not disdained walls built of
brick, although with their revenues and from booty they might often have
had them not only of masonry or dimension stone but even of marble, I
think that one ought not to reject buildings made of brick-work,
provided that they are properly "topped." But I shall explain why this
kind of structure should not be used by the Roman people within the
city, not omitting the reasons and the grounds for them.

17. The laws of the state forbid that walls abutting on public property
should be more than a foot and a half thick. The other walls are built
of the same thickness in order to save space. Now brick walls, unless
two or three bricks thick, cannot support more than one story; certainly
not if they are only a foot and a half in thickness. But with the
present importance of the city and the unlimited numbers of its
population, it is necessary to increase the number of dwelling-places
indefinitely. Consequently, as the ground floors could not admit of so
great a number living in the city, the nature of the case has made it
necessary to find relief by making the buildings high. In these tall
piles reared with piers of stone, walls of burnt brick, and partitions
of rubble work, and provided with floor after floor, the upper stories
can be partitioned off into rooms to very great advantage. The
accommodations within the city walls being thus multiplied as a result
of the many floors high in the air, the Roman people easily find
excellent places in which to live.

18. It has now been explained how limitations of building space
necessarily forbid the employment of brick walls within the city. When
it becomes necessary to use them outside the city, they should be
constructed as follows in order to be perfect and durable. On the top of
the wall lay a structure of burnt brick, about a foot and a half in
height, under the tiles and projecting like a coping. Thus the defects
usual in these walls can be avoided. For when the tiles on the roof are
broken or thrown down by the wind so that rainwater can leak through,
this burnt brick coating will prevent the crude brick from being
damaged, and the cornice-like projection will throw off the drops beyond
the vertical face, and thus the walls, though of crude brick structure,
will be preserved intact.

19. With regard to burnt brick, nobody can tell offhand whether it is of
the best or unfit to use in a wall, because its strength can be tested
only after it has been used on a roof and exposed to bad weather and
time--then, if it is good it is accepted. If not made of good clay or if
not baked sufficiently, it shows itself defective there when exposed to
frosts and rime. Brick that will not stand exposure on roofs can never
be strong enough to carry its load in a wall. Hence the strongest burnt
brick walls are those which are constructed out of old roofing tiles.

20. As for "wattle and daub" I could wish that it had never been
invented. The more it saves in time and gains in space, the greater and
the more general is the disaster that it may cause; for it is made to
catch fire, like torches. It seems better, therefore, to spend on walls
of burnt brick, and be at expense, than to save with "wattle and daub,"
and be in danger. And, in the stucco covering, too, it makes cracks from
the inside by the arrangement of its studs and girts. For these swell
with moisture as they are daubed, and then contract as they dry, and, by
their shrinking, cause the solid stucco to split. But since some are
obliged to use it either to save time or money, or for partitions on an
unsupported span, the proper method of construction is as follows. Give
it a high foundation so that it may nowhere come in contact with the
broken stone-work composing the floor; for if it is sunk in this, it
rots in course of time, then settles and sags forward, and so breaks
through the surface of the stucco covering.

I have now explained to the best of my ability the subject of walls, and
the preparation of the different kinds of material employed, with their
advantages and disadvantages. Next, following the guidance of Nature, I
shall treat of the framework and the kinds of wood used in it, showing
how they may be procured of a sort that will not give way as time goes
on.

CHAPTER IX

TIMBER

1. Timber should be felled between early Autumn and the time when
Favonius begins to blow. For in Spring all trees become pregnant, and
they are all employing their natural vigour in the production of leaves
and of the fruits that return every year. The requirements of that
season render them empty and swollen, and so they are weak and feeble
because of their looseness of texture. This is also the case with women
who have conceived. Their bodies are not considered perfectly healthy
until the child is born; hence, pregnant slaves, when offered for sale,
are not warranted sound, because the fetus as it grows within the body
takes to itself as nourishment all the best qualities of the mother's
food, and so the stronger it becomes as the full time for birth
approaches, the less compact it allows that body to be from which it is
produced. After the birth of the child, what was heretofore taken to
promote the growth of another creature is now set free by the delivery
of the newborn, and the channels being now empty and open, the body will
take it in by lapping up its juices, and thus becomes compact and
returns to the natural strength which it had before.

2. On the same principle, with the ripening of the fruits in Autumn the
leaves begin to wither and the trees, taking up their sap from the earth
through the roots, recover themselves and are restored to their former
solid texture. But the strong air of winter compresses and solidifies
them during the time above mentioned. Consequently, if the timber is
felled on the principle and at the time above mentioned, it will be
felled at the proper season.

3. In felling a tree we should cut into the trunk of it to the very
heart, and then leave it standing so that the sap may drain out drop by
drop throughout the whole of it. In this way the useless liquid which is
within will run out through the sapwood instead of having to die in a
mass of decay, thus spoiling the quality of the timber. Then and not
till then, the tree being drained dry and the sap no longer dripping,
let it be felled and it will be in the highest state of usefulness.

4. That this is so may be seen in the case of fruit trees. When these
are tapped at the base and pruned, each at the proper time, they pour
out from the heart through the tapholes all the superfluous and
corrupting fluid which they contain, and thus the draining process makes
them durable. But when the juices of trees have no means of escape, they
clot and rot in them, making the trees hollow and good for nothing.
Therefore, if the draining process does not exhaust them while they are
still alive, there is no doubt that, if the same principle is followed
in felling them for timber, they will last a long time and be very
useful in buildings.

5. Trees vary and are unlike one another in their qualities. Thus it is
with the oak, elm, poplar, cypress, fir, and the others which are most
suitable to use in buildings. The oak, for instance, has not the
efficacy of the fir, nor the cypress that of the elm. Nor in the case of
other trees, is it natural that they should be alike; but the individual
kinds are effective in building, some in one way, some in another, owing
to the different properties of their elements.

6. To begin with fir: it contains a great deal of air and fire with very
little moisture and the earthy, so that, as its natural properties are
of the lighter class, it is not heavy. Hence, its consistence being
naturally stiff, it does not easily bend under the load, and keeps its
straightness when used in the framework. But it contains so much heat
that it generates and encourages decay, which spoils it; and it also
kindles fire quickly because of the air in its body, which is so open
that it takes in fire and so gives out a great flame.

7. The part which is nearest to the earth before the tree is cut down
takes up moisture through the roots from the immediate neighbourhood and
hence is without knots and is "clear." But the upper part, on account of
the great heat in it, throws up branches into the air through the knots;
and this, when it is cut off about twenty feet from the ground and then
hewn, is called "knotwood" because of its hardness and knottiness. The
lowest part, after the tree is cut down and the sapwood of the same
thrown away, is split up into four pieces and prepared for joiner's
work, and so is called "clearstock."

8. Oak, on the other hand, having enough and to spare of the earthy
among its elements, and containing but little moisture, air, and fire,
lasts for an unlimited period when buried in underground structures. It
follows that when exposed to moisture, as its texture is not loose and
porous, it cannot take in liquid on account of its compactness, but,
withdrawing from the moisture, it resists it and warps, thus making
cracks in the structures in which it is used.

9. The winter oak, being composed of a moderate amount of all the
elements, is very useful in buildings, but when in a moist place, it
takes in water to its centre through its pores, its air and fire being
expelled by the influence of the moisture, and so it rots. The Turkey
oak and the beech, both containing a mixture of moisture, fire, and the
earthy, with a great deal of air, through this loose texture take in
moisture to their centre and soon decay. White and black poplar, as well
as willow, linden, and the agnus castus, containing an abundance of
fire and air, a moderate amount of moisture, and only a small amount of
the earthy, are composed of a mixture which is proportionately rather
light, and so they are of great service from their stiffness. Although
on account of the mixture of the earthy in them they are not hard, yet
their loose texture makes them gleaming white, and they are a convenient
material to use in carving.

10. The alder, which is produced close by river banks, and which seems
to be altogether useless as building material, has really excellent
qualities. It is composed of a very large proportion of air and fire,
not much of the earthy, and only a little moisture. Hence, in swampy
places, alder piles driven close together beneath the foundations of
buildings take in the water which their own consistence lacks and remain
imperishable forever, supporting structures of enormous weight and
keeping them from decay. Thus a material which cannot last even a little
while above ground, endures for a long time when covered with moisture.

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