294 Trans. Acad. Sci. of St. Louis. 
hygienic conditions of cities andtowns. There are numerous 
instances of typhoid and cholera epidemics in which these 
diseases were traced to the drinking-water. In Hamburg, 
1892, there were 16,957 cases and 8,606 deaths from cholera. 
Of the chief typhoid fever epidemics as embodied in a report 
of the epidemic of Butler, Pa., may be mentioned the 
following : — 
Location. Date. Population.| Cases. Deaths. 
Lausanne, Switzerland....... 1872 780 $46 cis bosme cams 
Caterham, England..........-. 1879 5,800 352 21- 
Fiviib uth, Bak .3 sie debs 45> 1885 8,000 1,104 114 
Ithica, N. Y..cccccceccescence 1903 13,000 1,300 78 
Witiar, Pas scones cowesaw dees 1903-1904 18,000 1,348 111 
In our own city, St. Louis, 1892, there was an epidemic of 
typhoid fever which was traced directly to the water supply, 
the latter having become contaminated with sewage which 
entered the intake. 
It is important, therefore, that a community see to it that 
its water supply be kept pure and wholesome. Experience 
and statistics have shown that wherever the water supply of a 
community has been purified, by filtration or otherwise, there 
has been a decrease in the mortality rate. Moreover, the 
time will come, as the population of the country grows, when 
cities will purify not only their water supply, but that they 
will also be compelled to pay attention to the purification of 
sewage, so that the towns which are situated lower down 
along the stream may be assured of a water the quality of 
which is reasonably pure. 
A bacteriological examination of a river is not complete 
-without an intelligent interpretation of the results. A river 
must be considered as a complex system or body, in which 
various biological and chemical changes are constantly taking 
place. All the facts and data that have been collected must 
be carefully weighed, and their relationship carefully studied. 
It is of importance that all the tests for comparison should 
have been made under uniform methods and that the data 
for comparison should be abundant, for it happens too often 
