Jackie Thomas, age 12, of Brooklyn, N.Y., for her question:
WHEN WAS THE FIRST AQUEDUCT BUILT?
An aqueduct is an artificial channel through which water is conducted to the place where it is used. An aqueduct may be built of masonry, concrete, cast iron, steel or wood.
Aqueducts go back to ancient times. We don't know exactly where or when the first aqueducts were built but we do know the idea goes back many thousands of years.
A leaky aqueduct made of a series of limestone blocks in which 15 inch holes had been drilled by hand goes back to ancient times in Jerusalem. Then the Greeks built masonry conduits to bring water to their cities and even bored tunnels by hand.
One of the Greek tunnels is 4,200 feet long. It was built in Athens 2,500 years ago and it was used as part of an efficient water system.
Most aqueducts of ancient times were built of stone, brick or pozzuolana, a mixture of limestone and volcanic dust. They were built nearly on a level.
The city of Rome had many aqueducts and was the only ancient city reasonably supplied with water. The first person in charge of the Roman waterworks was Marcus Agrippa, who was appointed water commissioner in 33 B.C.
By A.D. 97 nine aqueducts brought about 85 million gallons of water a day from mountain springs. Later, five other aqueducts were built to increase the Rome water supply.
About 200 cities in the Roman colonies also had aqueducts. One famous Roman aqueduct is the Pont du Gard, which still stands across a river at Nimes, France.
Only a few aqueducts were then built until the Middle Ages. Late in the 1500s, an aqueduct was built for the English town of Plymouth by Sir Francis Drake, then mayor. It was called the River Leet, and it was an open channel 24 miles long.
London had no aqueduct until 1609 when the aqueduct called New River was built, bringing water 38 miles to London.
In many aqueducts, the outlet is so much lower than the water source that gravity alone carries the water. Where gravity is insufficient, the water has to be forced through the aqueduct by pumps.
As cities and industries grow, they require more water, and more aqueducts must be built. The average amount of water used daily in the American home is greater than ever before. Such modern conveniences as commercial air conditioners require large quantities of water. Dry lands that must be irrigated to produce crops often get their water from aqueducts.
One of the first great modern aqueducts was the first Croton Aqueduct built by New York City in 1842. It was made of masonry lined with brick. Iron pipes carried water across the Harlem River over a viaduct.
During the late 1800s, other cities, especially those of Great Britain, built large aqueducts. Birmingham, Glasgow, Liverpool and Manchester built aqueducts to supply the water for industrial growth.
Many of the world's greatest aqueducts were built in the early 1900s. The Catskill Aqueduct, completed in 1913 for New York City, extends 120 miles.