Aqueduct in Tusculum, Italy
Of the constructions for the conveyance of water in Italy in early times, there is an example at Tusculum, consisting of an oblong basin divided into several chambers, which received the water of a spring, and then distributed it by pipes (tubi, fistulae) or canals. The basin is built of blocks of stone, which, along the sides, overlap each other, till they meet and form a roof a principle of building which was afterwards supplanted by vaulting, and which occurs also in the earliest Greek masonry. The pipes were either of lead or baked clay. When the course lay in soil, gullies were cut and conduits of masonry built within them. When rocky ground intervened, tunnels were pierced, and in both cases shafts (spiramen, lumen) were made at intervals of about 240 feet, to admit light and fresh air. The inside of the walls of these channels received a coating impervious to water, composed of chalk and crushed fragments of tile. Where the course was interrupted by an inequality in the ground, a vertical pipe (venter) was placed reaching to the surface or above it. The water rushing up this pipe was freshened by contact with the air, and again fell back to the new course which it had to take. Works of this kind, undertaken for the public convenience, were paid for out of the public purse, a tax being levied for the use of the water.
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