0 K . VIII. 
0 
But if it be required to conduct water with less expence, it must be done thus: Tubes of 
earthen ware are made, having coats not less than two inches thick; and these tubes are so 
made, that one end being tongued, the one may enter the other; then the joints are cemented 
with quicklime tempered with oil; and in the descents level with the venter, a stone of the 
red kind is placed at the angles, so perforated, that the last tube of the decursus, and first on 
the plane of the venter, may be joined to the stone. So likewise at the opposite acclivity, the 
last in the plane of the venter, and the first of the expressure, are to be in the same manner 
united to the red stone. 
Thus the tubes on the even plane, as well as those in the decursus and expressure, will not 
be ruptured; for such violent vapours are apt to arise in conduits of water as would even 
burst through stone, unless the water was, at first, gently and sparingly admitted from the 
spring, and the bendings secured with ligatures, or weights of ballast. In all other respects 
they are laid in the same manner as leaden pipes. When first the water from the spring is 
admitted, ashes are sent before it, that if any of the joints should not be sufficiently cemented, 
they may be stopped by the ashes. 
Aqueducts of tubes have these advantages: first, with regard to the work, if any damage 
should happen, any person may rectify it; and then also, the water from earthen tubes is 
more wholesome than that from pipes, as lead is found to be pernicious; for from it is made 
ceruse, which is said to be hurtful to the human body; and if that which is made from it is 
noxious, there is no doubt but that itself is also unwholesome. This is exemplified by the 
workers of lead, whose bodies are of a pallid colour: for when they are melting the lead, the 
vapour of it settling on their limbs, and the whole day scorching them, extracts from the 
members the juices of the blood. We therefore should not conduct water in pipes of lead, 
if we would have it wholesome; the taste also of that from tubes is better, as is proved at 
our daily meals ; for all persons, although they have tables furnished with vases of silver, yet 
use fictile ware on account of the purity of the taste. 
But if there be no spring from whence we may make an aqueduct, it is necessary to dig 
wells; and in digging of wells, reason is not to be difregarded, but the nature of things is with 
great attention and judgment to be considered. For the earth generates in itself many and 
various substances; it is in fact, like other things, composed of the four elements; and the 
first is itself, earth; from moisture it has springs of water; also heat; from whence come 
sulphur, alum, and bitumen: and air, whence the prodigious vapours, which, when con- 
densed, pierce through the interstices of the earth to the apertures of wells, and disturb the 
men who may be there digging, obstructing, by the natural vapour, the breath of their 
nostrils ; so that whoever does not speedily fly, there dies. The means by which this is to