9Colonnades must be constructed behind the scaena, so that when sudden showers interrupt plays, the people may have somewhere to retire from the theatre, and so that there may be room for the preparation of all the outfit of the stage. Such places, for instance, are the colonnades of Pompey, and also, in Athens, the colonnades of Eumenes and the fane of Father Bacchus; also, as you leave the theatre, the music hall which Themistocles surrounded with stone columns, and roofed with the yards and masts of ships captured from the Persians. It was burned during the war with Mithridates, and afterwards restored by King Ariobarzanes. At Smyrna there is the Stratoniceum, at Tralles, a colonnade on each side of the scaena above the race course, and in other cities which have had careful architects there are colonnades and walks about the theatres.
2The approved way of building them requires that they should be double, and have Doric columns on the outside, with the architraves and their ornaments finished according to the law of modular proportion. The approved depth for them requires that the depth, from the lower part of the outermost columns to the columns in the middle, and from the middle columns to the wall enclosing the walk under the colonnade, should be equal to the height of the outer columns. Let the middle columns be one fifth higher than the outer columns, and designed in the Ionic or Corinthian style.
3The columns will not be subject to the same rules of symmetry and proportion which I prescribed in the case of sanctuaries; for the dignity which ought to be their quality in temples of the gods is one thing, but their elegance in colonnades and other public works is quite another. Hence, if the columns are to be of the Doric order, let their height, including the capital, be measured off into fifteen parts. Of these parts, let one be fixed upon to form the module, and in accordance with this module the whole work is to be developed. Let the thickness of the columns at the bottom be two modules; an intercolumniation, five and a half modules; the height of a column, excluding the capital, fourteen modules; the capital, one module in height and two and one sixth modules in breadth. Let the modular proportions of the rest of the work be carried out as written in the fourth book in the case of temples.
4But if the columns are to be Ionic, let the shaft, excluding base and capital, be divided into eight and one half parts, and let one of these be assigned to the thickness of a column. Let the base, including the plinth, be fixed at half the thickness, and let the proportions of the capital be as shown in the third book. If the column is to be Corinthian, let its shaft and base be proportioned as in the Ionic, but its capital, as has been written in the fourth book. In the stylobates, let the increase made there by means of the “scamilli impares” be taken from the description written above in the third book. Let the architraves, coronae, and all the rest be developed, in proportion to the columns, from what has been written in the foregoing books.
5The space in the middle, between the colonnades and open to the sky, ought to be embellished with green things; for walking in the open air is very healthy, particularly for the eyes, since the refined and rarefied air that comes from green things, finding its way in because of the physical exercise, gives a clean-cut image, and, by clearing away the gross humours from the eyes, leaves the sight keen and the image distinct. Besides, as the body gets warm with exercise in walking, this air, by sucking out the humours from the frame, diminishes their superabundance, and disperses and thus reduces that superfluity which is more than the body can bear.
6That this is so may be seen from the fact that misty vapours never arise from springs of water which are under cover, nor even from watery marshes which are underground; but in uncovered places which are open to the sky, when the rising sun begins to act upon the world with its heat, it brings out the vapour from damp and watery spots, and rolls it in masses upwards. Therefore, if it appears that in places open to the sky the more noxious humours are sucked out of the body by the air, as they obviously are from the earth in the form of mists, I think there is no doubt that cities should be provided with the roomiest and most ornamented walks, laid out under the free and open sky.
7That they may be always dry and not muddy, the following is to be done. Let them be dug down and cleared out to the lowest possible depth. At the right and left construct covered drains, and in their walls, which are directed towards the walks, lay earthen pipes with their lower ends inclined into the drains. Having finished these, fill up the place with charcoal, and then strew sand over the walks and level them off. Hence, on account of the porous nature of the charcoal and the insertion of the pipes into the drains, quantities of water will be conducted away, and the walks will thus be rendered perfectly dry and without moisture.
8Furthermore, our ancestors in establishing these works provided cities with storehouses for an indispensable material. The fact is that in sieges everything else is easier to procure than is wood. Salt can easily be brought in beforehand; corn can be got together quickly by the State or by individuals, and if it gives out, the defence may be maintained on cabbage, meat, or beans; water can be had by digging wells, or when there are sudden falls of rain, by collecting it from the tiles. But a stock of wood, which is absolutely necessary for cooking food, is a difficult and troublesome thing to provide; for it is slow to gather and a good deal is consumed.
9On such occasions, therefore, these walks are thrown open, and a definite allowance granted to each inhabitant according to tribes. Thus these uncovered walks insure two excellent things: first, health in time of peace; secondly, safety in time of war. Hence, walks that are developed on these principles, and built not only behind the “scaena” of theatres, but also at the temples of all the gods, will be capable of being of great use to cities.
As it appears that we have given an adequate account of them, next will follow descriptions of the arrangements of baths.