THE IRRIGA I ION A GE. 265 



in diameter, fitting these blocks together with curved necks 

 and recesses, whose joints were laid in cement and held 

 secure by means of iron bands run with lead. This was an inverted 

 syphon, now so often used to cross a ravine or canon in the west, but 

 made from stone instead of steel or redwood hooped with steel, so 

 commonly used today. 



"Rome was supplied with water in Nero's time by nine separate 

 aqueducts aggregating a length of 255 miles, and which delivered 

 daily 173,000,000 gallons of water, which was later increased to 312,- 

 500,000 gallons. The Aqua Martia conduit, which brought the drink- 

 ing water for the city, had a diameter of 16 feet, and was 40 miles 

 long. 



"When the Romans invaded France, they constructed great sys- 

 tems of water works for cities in various places at Lyons Souy, 

 Nismes, Frejus, and Metz. The Nemes conduit was constructed at 

 the time of Augustus, 19 B. C., and delivered 14,000,000 gallons per 

 day. It is noted for the great Pont du Gard, which carried it across 

 a ravine, and which is spoken of by Humble as one one of the grand- 

 est monuments the Romans left in France. 



"China, like Egypt, dates its early enterprises of irrigation and 

 transportation by water far back in antiquity, for she has numerous 

 canals, some of them the most stupendous works of the kind ever 

 undertaken. The Great Imperial Canal has a length of 650 

 miles, and! connects the Hoang Ho with Yang-tse-Kiang. It 

 has a depth seldom exceeding 5Q to 6 feet, and in it the 

 water moves at the rate of 2 A miles per hour. In its path there are 

 several large lakes, and across these the canal is carried on the crest 

 of enormous dykes. 



"If we leave the Old World and come to the New for records of 

 an early development of the cultivation of land by irrigation, we shall 

 not be disappointed, for traces of an early civilization in Colorado, 

 New Mexico and Arizona, and extending through Mexico and Central 

 America on into Peru, are found in the ruins of ancient towns and 

 irrigating canals in many places. When the Spaniards invaded Mexico, 

 Central America and Peru, they were greatly surprised to find in 

 these countries, and particularly in Peru, the land of the Incas, very 

 elaborate and extensive irrigation systems, laid out and in actual gen- 

 eral use by these people. 



"Prescott, in his 'Conquest of Peru', speaking of the use of water 

 for irrigation, writes that 'water was conveyed by means of canals 

 and subterraneous aqueducts executed on a noble scale. They con- 

 sisted of large slabs of freestone nicely ^tted together without cement, 

 nd discharged a volume of water sufficient, by means of latent ducts 

 r sluices, to moisten the lands in the lower levels through which 

 they passed. Some of these aqueducts were of great length. 



