The Supply and Uses of Water 193 



running from the Chicago River to one of the tributaries of the 

 Illinois River, along an old Indian portage route from the Lake 

 to the Mississippi River. Trace this on a map. Since then 

 the health statistics of the city show that the community has 

 been more than compensated on this score alone for the fifty 

 and more millions of dollars which the canal cost. 



London's supply. Water secured from sources exposed to 

 pollution, as rivers, lakes, or surface wells may be, should be 

 purified before distribution. Many communities depending 

 upon such a supply have adopted measures to make the water 

 safe and to prevent accidental contamination. The common 

 methods are by storage in still reservoirs and filtration through 

 sand. That such means are effective may be shown by the 

 experience of London, England. 



The larger part of London's supply is from the Thames and 

 the Lee. These rivers flow through populous districts and are 

 made carriers of sewage above the intake of London's supply. 

 But by employing storage reservoirs and sand filtration, London 

 has furnished safe water for many years. It points with pride 

 to its general health statistics, and especially to those of diseases 

 which are supposed to be caused by germs carried by water. 

 Storage destroys many kinds of bacteria and removes a very 

 large per cent of the injurious matter. Filtration through sand 

 completes the process. 



The Ganges River supply. Some rivers possess exceptional 

 powers of sterilizing or purifying their waters. For thousands 

 of years the waters of the Ganges and the Jumna have been 

 regarded by the Hindus as " pure and undefiled." This does 

 not seem possible, for into them are put all sorts of sewage and 

 decaying organic matter, such as bodies of animals and men, 

 among them victims of cholera. Thousands, moreover, bathe 

 in the waters daily. But in spite of all this, the water is safe 

 and is used for every purpose. It is interesting to find science 

 confirming and supporting a belief that has long held sway, for 

 bacteriological and other scientific tests have been made of these 



