moderate weather is necessary for the masonry properly to absorb the mortar, and to solidify into one compact mass; for excessive heat of the sun is no less destructive than frost to masonry. Nor is greater care required upon any works than upon such as are to withstand the action of water; for this reason, in accordance with principles which all know but few observe, honesty in all details of the work must be insisted upon.
I think no one will doubt that the greatest care should be taken with the aqueducts nearest to the City (I mean those inside the seventh mile-stone, which consist of block-stone masonry), both because they are structures of the greatest magnitude, and because each one carries several conduits; for should it once be necessary to interrupt these, the City would be deprived of the greater part of its water-supply. But there are methods for meeting even these difficulties: provisional works are built up to the level of the conduit which is being put out of use, and a channel, formed of leaden troughs, running along the course of the portion that has been cut off, again provides a continuous passage. Furthermore, since almost all the aqueducts ran through the fields of private parties and it seemed difficult to provide for future outlays without the help of some constituted law; in order, also, that contractors should not be prevented by proprietors from access to the conduits for the purpose of making repairs, a resolution of the Senate was passed, which I give below:—
"The consuls, Quintus Aelius Tubero and Paulus Fabius Maximus, having made a report relating to the restoration of the canals, conduits, and arches of
