from which are also drawn all expenses for lead and for conduits, reservoirs, and basins.
As I have now explained all, I think, that has to do with slave-gangs, I will now, as I promised, come back to the maintenance of the conduits, a thing which is worthy of more special care, as it gives the best testimony to the greatness of the Roman Empire. The numerous and extensive works are continually falling into decay, and they must be attended to before they begin to demand extensive repair. Very often, however, it is best to exercise a wise restraint in attending to their upkeep, since those who urge the construction or extension of the works cannot always be trusted. The water-commissioner, therefore, not only ought to be provided with competent advisers, but ought also to be equipped with practical experience of his own. He must consult not only the architects of his own office, but must also seek aid from the trustworthy and thorough knowledge of numerous other persons, in order to judge what must be taken in hand forthwith, and what postponed, and, again, what is to be carried out by public contractors and what by his own regular workmen.
The necessity of repairs arises from the following reasons: damage is done either by the lawlessness of abutting proprietors, by age, by violent storms, or by defects in the original construction, which has happened quite frequently in the case of recent works.
As a rule, those parts of the aqueducts which are carried on arches or are placed on side-hills and, of those on arches, the parts that cross rivers suffer most from the effects of age or of violent storms.
