fifth part

1. Aqueduct, ( Latin aqua + ducere, "to lead water" ) man-made conduit for carrying water. In a
restricted sense, aqueducts are structures used to conduct a water stream across a hollow or
valley. In modern engineering, however, aqueduct refers to a systemof pipes, ditches, canals,
tunnels, and supporting structures used to convey water from its source to its main distribution
point. Such systems generally are used to supply cities and agricultural lands with water.
Aqueducts have been important particularly for the development of areas with limited direct
access to freshwater sources. Historically, aqueducts helped keep drinking water free of human
waste and other contamination and thus greatly improved public health in cities with
primitive sewerage systems.
Although the Romans are considered the greatest aqueduct builders of the ancient
world, qanāt systems were in use in ancient Persia, India, Egypt, and other Middle Eastern
countries hundreds of years earlier. Those systems utilized tunnels tapped into hillsides that
brought water for irrigation to the plains below. Somewhat closer in appearance to the classic
Roman structure was a limestone aqueduct built by theAssyrians about 691 BCE to bring fresh
water to the city of Nineveh. Approximately two million large blocks were used to make a water
channel 10 metres (30 feet) high and 275 metres (900 feet) long across a valley.
The elaborate system that served the capital of the Roman Empire, remains a major engineering
achievement. Over a period of 500 years—from 312 BCE to 226 CE—11 aqueducts were built to
bring water to Rome from as far away as 92 km (57 miles). Some of those aqueducts are still in
use. Only a portion of Rome’s aqueduct systemactually crossed over valleys on stone arches (50
km out of a total of about 420 km); the rest consisted of underground conduits made mostly of
stone and terra-cotta pipe but also ofwood, leather, lead, and bronze. Water flowed to the city by
the force of gravity alone and usually went through a series of distribution tanks within the city.
Rome’s famous fountains and baths were supplied in that way. Generally, water was not stored,
and the excess was used to flush out sewers to aid the city’s sanitation.
Roman aqueducts were built throughout the empire, and their arches may still be seen in Greece,
Italy, France, Spain, North Africa, and Asia Minor. As central authority fell apart in the 4th and 5th
centuries, the systems also deteriorated. For most of the Middle Ages, aqueducts were not used in
western Europe, and people returned to getting their water from wells and local rivers. Modest
systems sprang up around monasteries. By the 14th century, Brugge, with a large population for
the time (40,000), had developed a system utilizing one large collecting cistern from which water
was pumped, using a wheel with buckets on a chain, through underground conduits to public sites.
Major advances in public water systems since the Renaissance have involved the refinement of
pumps and of pipe materials. By the late 16th century, London had a system that used five
waterwheel pumps fastened under the London Bridge to supply the city, and Paris had a similar
device at Pont Neuf that was capable of delivering 450 litres (120 gallons) per minute. Both cities
were compelled to bring water from greater distances in the next century. A private company built
an aqueduct to London from the River Chadwell, some 60 km (38 miles) distant, that utilized more

2. than 200 small bridges built of timber. A French counterpart combined pumps and aqueducts to
bring water from Marly over a ridge and into an aqueduct some 160 metres (525 feet) above the
Seine.
One of the major innovations during the 18th and 19th centuries was the introduction of
steam pumps and the improvement of pressurized systems. One benefit of pumping water under
pressure was that a systemcould be built that followed the contours of the land; the earlier free-
flowing systems had to maintain certain gradients over varied terrain. Pressurization created the
need for better pipe material. Woodpipes banded with metal and protected with asphalt coating
were patented in the United States in 1855. Before long, however, wood was replaced first by cast
iron and then by steel. For large water mains (primary feeders), reinforced concrete became the
preferred construction material early in the 20th century. Ductile iron, a stronger and more elastic
type of cast iron, is one of the most common materials now used for smaller underground pipes
(secondary feeders), which supply water to local communities.
Modern aqueducts, although lacking the arched grandeur of those built by the Romans, greatly
surpass the earlier ones in length and in the amount of water they can carry. Aqueduct systems
hundreds of miles long have been built to supply growing urban areas and crop-irrigation projects.
The water supply of New York City comes from three main aqueduct systems that can deliver
about 6.8 billion litres (1.8 billion gallons) of water a day from sources up to 190 km (120 miles)
away. The aqueduct systemin the state of California is by far the longest in the world.
The California Aqueduct conveys water about 700 km (440 miles) from the northern (wetter) part
of the state into the southern (drier) part, yielding more than 2.5 billion litres (650 million gallons)
of water a day.
The first argument to take on to built an acqueduct was the spring; Tiber, the river that runs
thought Rome, had very dirty waters, but the hills that were around Rome had a lot of natural and
suitable springs. It was necessary to keep in consideration quality of the water, quantity and
regularity of the flow, but especially share at the point of the captation. Infact the water flux was
regulated only by the gravity and for all the crossing of the acqueduct there were a costant incline,
average of 2%. To calcolate the inclination were used things like chorobates and dioptra. The
acqueducts were priority of the state at the service of population. The means per capita of water
was double of the actual one. Rome had 1300 public fountains, 15 monumental fountains, 900
pools, 11 thermal baths, 15 artificial lakes, some used for public plays. Totally the acqueducts had
a lenght of 420 km. It was illegal to pollute the acqueducts or to connect to the canal without
paying a tribute.

3. At the spring, a basin canalised the water in one duct; in the case of the subterranean springs,
were dug wells or tunnels. Before being canalised, the water accrossed the “piscinae limanae”,
some baths were the water flowed slowly, so that the sediments would fall on the bottom. These
baths were also on the flow of the acqueduct.
Far from the cities generally the water flowed in subterranean canals. The canal of the acqueduct
was called “specus” and upholstery of the innerwalls were made of the waterproof material and
resistant composed by terracotta, lime and well, vulcanicdust that surpotted the solidification of
the material. By the “specus” outlets were, therefore, in the case of flood, the walls wouldn’t have
been damaged, If the water must, because of the morphology of the territory, flow on the surface,
“specus” was recovered by a flat stone. Also some walls were built on that the water flowed to
regulated the incline when it was highter ground level. Sometimes the walls weren’t enough and
since they couldn’t pass two meters, Romans used architectual element perfected by them; the
arch.
The arches were a light building relative to simple to build and resistent. Arches were used to
regolate the incline and to pass the barriers of the land. They couldn’t pass 20 metres otherwise
they became variable. Because of this by necessity were build high arches till 3 arches that could
reach the height 40 metres. Sometimes to pass wide valley was used technique of the syphon
opposite; water was made flow steeply by a mountain and because of the generated force
returned on the other side.
By: Beatrice Adamini, Francesca Besana, Rebecca Colombo, Ester Penati, Ester Prato, Martina
Talarico