One thing the ordinary Roman appears never to have minded, any more than it is minded at the present day. This was noise. There are studious men enough in ancient literature who complain that sleep or study is impossible in Rome. They exclaim upon the bawling of the hawkers, the canting songs of the beggars, the banging of hammers, the sing-song of schoolboys learning to read in the open-air verandahs or balconies which often served as schools, and the shouting in the baths. All night long there was the rattle of carts and the creaking of heavy waggons. But the average Roman cared, and still cares, very little for quiet or sleep, and no emperor attempted to check the annoyance. Perhaps he could devise no check. Perhaps he himself, being on the Palatine, and his counsellors, being in their own comparatively secluded houses on the hills, scarcely realised the full enormity of the nocturnal roar of Rome. In any case the fact of the noise is unquestionable. It was then very much as it is now if one tries to sleep in rooms in the Corso or the Via Babuino. The saying that "God made the country and man made the town" is met with in a Roman writer of the age of Augustus, and the noise is one factor in the difference. The ancient Romans, we have said, were masters of practical engineering, and a chief glory of the city was its abundant supply of water. Apart from the Tiber and the natural springs, there were in the year 64 at least eight aqueducts bringing drinkable water into the city. It was the emperor's concern to see to this matter, as he did to the corn-supply, but in practice he appointed what he might call his Minister of Water-supply, and gave him liberal means to provide a large staff of engineers, surveyors, masons, pipelayers, inspectors, and custodians. It is a common error to imagine that the Romans were ignorant of the simple hydraulic law that water will find its own level, and to suppose that their aqueducts were built in consequence of that ignorance. In point of fact they knew the law as well as we do. Their earlier aqueducts were conduits almost wholly underground; their later were all on arches. When they wished to carry water to a height within the city, up a watertower to a distributing cistern, or to the top storey of a building, they did so by pipes, just as we should; but when they brought water from forty miles away they preferred to bring it in channels lined with impermeable cement and carried upon arches, which wound across the country according to the levels in order to avoid the excessive pressure of too steep a gradient. The reasons for their choice are simple enough. Their chief difficulty was in making pipes of iron of sufficient capacity. On the other hand, it was easy to construct a cemented channel in masonry of any size you desired. In the next place the water about Rome rapidly lays a calcareous deposit, and it is much easier to clear this from a readily accessible channel than from pipes buried in the ground.