432 



HEALTH AND DISEASE 



allow in his neighborhood, for sanitary reasons. The best results 

 in summer street-cleaning are obtained by washing or flushing the 



streets, for thus the dirt 

 containing germs is pre- 

 vented from getting into 

 the air. The garbage is 

 removed in carts, and part 

 of it is burned in huge 

 furnaces. The animal and 

 plant refuse is cooked in 



Removal of ashes by department of street oreat tanks ; from this 



cleaning. New York. material the fats are ex- 



tracted, and the solid matter is sold for fertilizer. Ashes are used 

 for filling marsh land. Thus the removal of waste matter may 

 pay for itself in a large city. 



The Necessity of a Pure Milk and Water Supply. The city of 

 New York is spending hundreds of millions of dollars to bring a 

 supply of pure water to her citizens. Other cities are doing the 

 same. The world has awakened to the necessity of a pure water 

 supply, largely because of the number of epidemics of typhoid 

 which have been caused by contaminated water. Typhoid fever 

 germs live in the food tube, hence the excreta of a typhoid patient 

 will contain large numbers of germs. In a city with a system of 

 sewage such germs might eventually pass from the sewers into a 

 river. Many cities take their water supply directly from rivers, 

 sometimes not far below another large town. Such cities must 

 take many germs into their water supply. Many cities, as Cleve- 

 land and Buffalo, take their water from lakes into which their 

 sewage flows. In cities which drain their sewage into rivers and 

 lakes, the question of sewage disposal is a large one, and many 

 cities now have means of disposing of their sewage in some manner 

 as to render it harmless to their neighbors. Filtering such water by 

 means of passing the water through settling basins and sand filters 

 removes about 98 per cent of the germs. The result of drinking 

 unfiltered and filtered water in certain large cities is shown graphi- 

 cally on the following page. 



In the country typhoid may be spread by the germs getting into 

 a well or spring from whence the supply of water comes. This 



