270 WATER HYGIENE 
m—Ni | | ft tt 
36 36 
RZENGEEEEEEEEEEES 
39 us 39 
JESS NAR i 
2 38 tf} — | | 28 
2 oe 8 
& S | GROWTH OF | | \ 5 
on 24 WATER FILTRATION TY A 24 
= g 22 4 DECREASE OF ERAN 22 
E B99 TYPHOID FEVER DEATH RATE 20 
23 b__| REGISTRATION CITIES OF | | 
ao 18 18 
aa UNITED STATES 
Fo igh ee 6 
eur | | | | | | = 14 
(a “ 
2 & 10 10 
a 8 8 
r=) G 6 
4 4 
P) 2 
0 0 
Fig. 59.—Relation of Water Filtration to Typhoid Fever. (After Johnson.) 
AVERAGE TYPHOID FEVER DEATH RATE 
—FOR—— 
FIVE YEARS BEFORE AND FIVE YEARS AFTER FILTRATION 
ALL CITIES OF US. OVER 100 000 POPULATION IN 1915 
are ae Pittsburg 
mn Albany 
EE es Columbus 
Philadelphia 
Louisville 
Cincinnati 
S5) Washington 
55] Ailanta LSS 
eS] Reading 
era Indianapolis 
[40] New Haven 
EQ New Orleans 
[38 | Toledo 
El Paterson Explanation 
(25) Scranton WM Before Filtration 
Tol Providence After Filtration 
Average of Above 
Average Reduction =61 4 Total Population of Above Cities 5,450,000 
Fig. 60.—Typhoid Fever Death Rate in American Cities. (After Johnson.) 
