To comprehend fully the epidemic of typhoid fever in a certain restricted area of Philadelphia during December, 1911, and January, 1912, on the introduction of raw river water into the city service pipes, it is well to study the morbidity and mortality for the particular district affected by this epidemic (the Twenty-First, Twenty-Second, parts of the Twenty-Ninth, Thirty-Second, Thirty-Eighth, Forty-Second and Forty-Third wards) and the city at large for a period of years, as given in Table 1.
The morbidity per hundred thousand population in the district affected, with a population of 291,970, and the rest of the city, with a population of 1,288,280, for the months of December and January, is shown in Table 2.
Under regular operating conditions, water is pumped from the Schuylkill River at Shawmont to the filtration plants at Upper and Lower Roxborough, marked 1 and 2, respectively, on the accompanying map.
The main from