Engineering Wonders of the World
Volume I

ANCIENT ENGINEERING. 17 Facts about the Aqueducts. higher. As her dominion extended, so these mighty filaments stretched farther and farther up into the hills. Like a hand upon the clock- face of the Empire was the ever-rising level of the water supply of Rome.” * The first of the aqueducts of Rome was built by the great Censor Appius in the year 312 b.c., and was named after him the Aqua Appia. It led water 7 miles from the hills to the poorer quarters of the capital. Forty years later came the Anio Vetus, 43 miles long, from above Tivoli. The Aqua Marcia,completed in 144 b.c.,had a course of 61 miles, and cost the equivalent of about £1,600,000. It delivered water at the level of the lofty Capitol. Other notable aqueducts built subsequently were the Claudia and the Anio Novus (28-50 a.d.), 58 and 46 miles long respectively; and the Trajana (109 a.d.), 42 miles. The last of these lias been restored. These aqueducts, large and small, had a total length of 346 miles, and, in order to follow a hydraulic gradient without pressure, they were carried over arches—some of Astonishing great height—for 44 miles. It Figures. has been calculated that in the days of the Empire the quan- tity of water poured by them daily into Rome was about 350,000,000 gallons, or about one and a half times the supply of Greater London! Assuming the maximum population of Rome to have been 1,500,000—and this is probably a generous estimate—every inhabitant would have an allowance of well over 200 gallons per day. The water, on reaching the city, was stored in reservoirs, whence it flowed through a net- work of leaden pipes to all parts. One may see in the British Museum a specimen of the stop-cocks which the Romans used. The abun- dant supply accounts for the number of foun- tains and of public baths, some of which could accommodate two or three thousand persons * Dr. Thomas Hodgkin, The Walls, Gates, and Aqueducts of Rome. (1,408) < at a time ; also for the artificial lakes in the amphitheatres, on which small naval engage- ments were fought to amuse the mob. Though, as a rule, a Roman aqueduct was an artificial stream running on a uniform gradient from source to point of delivery, the Romans had acquaintance with the em- ployment of the high-pressure Roman main. Vitruvius mentions the Hydraulic “ siphon ” for negotiating a Science, valley, and recommends the staunching of joints by means of fine ashes mixed with water ; also the need for filling a siphon slowly and using air vents. Lead pipe siphons 18 inches in diameter and 1 inch thick have been found at Lyons ; and as long, ago as 115 b.c. a pipe siphon backed with con- crete was built at Alatri, in Italy, to with- stand a “ head ” of 340 feet of water. 1 SECTION OF ROMAN AQUEDUCT. Water channels shown black. Roman roads were of the same high quality as the Roman aqueducts. This great military nation realized that successful conquest required 2