208 Introduction to the Study of Science 



as it came from the well was safe. But before being pumped 

 into the reservoir, it was transferred into a pumping pit where 

 it stood for some time. When the pumps worked at a high 

 rate of speed, the water level in the pit was lowered and seepage 

 through the walls of the pit was noticed. The pit was im- 

 mediately emptied for examination; but overnight it was 

 filled with " about six feet of refined sewage." The pit was 

 found to be located where surface and other sewage drainage 

 could reach it and seep through its porous and cracked walls. 

 Enough did enter to cause a sudden and widespread epidemic 

 among the people making use of the city water. 



This case is but one of a large number, the investigation of 

 which has brought about the almost universal demand for a 

 safe water supply. The experience of such cities as Pittsburgh, 

 Cincinnati, and Chicago, in reducing the annual death rate 

 and the number of typhoid cases by improvement of the 

 water supply and of the disposal of sewage, is substantially 

 the same. 



82. Koch and filtration of water. The classical instance 

 of disease-reduction through purification of the water is that 

 of Altona and Hamburg, Germany. These cities secured water 

 from the River Elbe. Altona filtered it before distribution. 

 Hamburg turned it directly into the mains. In 1892 cholera 

 broke out in Hamburg and before it was brought under control 

 17,000 cases and 8600 deaths occurred out of a population of 

 about 600,000. Hamburg, situated above Altona, emptied 

 part of its sewage into the river. Altona, in spite of this pol- 

 lution of the water supply, had only a few scattered cases of 

 cholera. Robert Koch, noted for his achievements in hygiene, 

 demonstrated the value of the sand filter in this case. The 

 cholera microbe was frequently discovered in the raw river 

 water ; but not a single microbe was to be found after the water 

 had been filtered. 



The experience of European and American cities in puri- 

 fying admittedly polluted water and the resulting improvement 



