‹‹‹ Vitr. 8.6.4 | Table of Contents | Vitr. 8.6.6 ›››
5An aqueduct which is made of lead, should be thus constructed; if there be a proper fall from the spring head to the city, and hills high enough to cause an impediment do not intervene, the low intervals must be brought to a level by means of substructions preserving the fall directed for channel aqueducts, or by means of a circuitous course, provided it be not too much about; but if there be long valleys, let it be laid according to the slope of the hill, and when it arrives at the bottom, let it be carried level by means of a low substruction as great a distance as possible; this is the part called the venter, by the Greeks κοιλία; when it arrives at the opposite acclivity, the water therein being but slightly swelled on account of the length of the venter, it may be directed upwards.
5The conducting of the water through lead pipes is to be managed as follows. If there is a regular fall from the source to the city, without any intervening hills that are high enough to interrupt it, but with depressions in it, then we must build substructures to bring it up to the level as in the case of channels and conduits. If the distance round such depressions is not great, the water may be carried round circuitously; but if the valleys are extensive, the course will be directed down their slope. On reaching the bottom, a low substructure is built so that the level there may continue as long as possible. This will form the “venter,” termed Κοιλἱα by the Greeks. Then, on reaching the hill on the opposite side, the length of the venter makes the water slow in swelling up to rise to the top of the hill.