The drainage works. which have vastly ins• pro‘ed the sanitary conditions• were completed in 'sits after three centuries of more or less spas• modie effort, and at the cost of the lives of manv thousands of un•n and many millions of Th, great evils from Which the City of Nlexico sotl'i•red for many generations were inmolations from hake Texcoeo, and disease pro moted by the fact that the city stood in the but ton] of an undrained natural sink. The lake, suddenly filled by lownpou•s from the mountains, wunet buried Thirty thousand persons were drowned ln• the sudden submergence of the city in 1)129, and similar catastrophes were caused by nthe• floods.
It was to rescue the city from inundations that the drainage works were begun three centuries ago: but it was not till 1789 that the city ceased to be menaced by deluges. t p to 1830 the total expenditure on the drainage works had been $8,001000. but the menace of malaria and (pi (hnks had not yet been removed. The canal was nut deep enough, the lake was still very little below the mean level of the city, ainl the fall was not sufficient to carry off the sewage. The gigan
tic works DOW completed were not seriously un dertaken till 1885. They rank among the great engineering achievements of modern times, and with the completion of the sewage system in the city the total cost will be about $20.000,000. The works consist of sewers carrying the waste of the city to a canal starting from the San Lfizaro gates and extending for 4:3 miles, its course hieing deflected so as to cut Lakes San Cristaal, Naltocan, and Zumpango. Near the town of Zuni pango the canal empties into the tunnel, com pletely lined with brick, which has been dug through the mountains a distance of 32,869 feet to a river which carries the sewage to the Gulf of .Mexico. These works thus carry all the sur plus waters and sewage of the City of Mexico outside of the valley, and also control the entire waters of the valley, n110111114 :III outlet to those that might otherwise overflow fields and towns.