POTOMAC EIVER WATEE SUPPLY EELATIVE TO TYPHOID FEVEE. 267 
Summary of the bacteriological examinations of tap water — Continued. 
No. 
Location. 
Date. 
Number 
of bac- 
teria per 
cubic 
centi- 
meter. 
Fermentation in lac- 
tose broth — 
B.coii 
in — 
0.1 cc. 
1 cc. 
10 cc. 
1906. 
cc. 
317 
3329 Brightwood avenue 
Sept. 21 
26 
- 
- 
+ 
10 
318 
2458 Eighth street NW 
do . . . 
26 


_ 
324 
Western High School 
Sept. 24 
33 
+ 
-t- 
325 
Peahody Library 
....do ... 
39 
-1- 
327 
1014 F street NE 
Sept. 25 
21 
328 
1117 V street NW 
do . . . 
66 
-1- 
335 
1622 Thirty-second street NtV. (hydrant) . . 
Sept. 26 
L 365 
+ 
+ 
-1- 
341 
1476 Nevrton street NW 
Sept. 27 
23 


+ 
342 
1506 Meridian place NW 
do 
76 
344 
Bruce Colored School 
Sept. 28 
144 
345 
School Tenth and N streets NW 
do 
27 
346 
Business High School 
do . . . 
29 
347 
Garrison School 
do 
28 
348 
Iowa Circle NW. (public fountain) 
....do ... 
63 
349 
Sumner School 
do 
50 
350 
Stevens School 
do 
11 
351 
2414 K street NW 
Oct. 1 
9 
352 
714 Twenty-third street NW ; 
do . . . 
15 
353 
1391 F street NE 
Oct. 2 
10 
354 
68 I street NW 
do . . . 
8 
+ 
355 
1221 New Jersey avenue NW 
Oct. 3 
18 
356 
Fire department B, New Hampshire ave- 
nue and N street 
do . . . 
16 


379 
Twelfth and N streets NM' 
Oct. 6 
11 
380 
Twenty-third and H streets NW 
do .. 
17 
408 
Ninth and Michigan avenue 
Oct. 9 
10 
419 
Second and G streets ‘NE 
Oct. 10 
30 
428 
Pennsylvania avenue and F street SE 
Oct. 11 
17 
-(a) 
453 
Twelfth and M streets NW 
Oct. 15 
40 
459 
First and B streets SE 
Oct. 16 
72 
a5 cc. in 10 cc. coliunn. 
' A study of our tables will show that we made daily bacteriological 
examinations of seYeral samples of the tap water, collected as a rule 
from houses in which cases of typhoid fever had occurred. We 
could not, however, make a daily study of the successive changes in 
the river water as it passed through the three subsiding basins, the 
filters and the storage reservoir, on account of the distance of the 
water system from our laborator}^ and the press of other matters. 
Ail the data we have, however, bearing upon this important question 
are given. 
Our results show that the great majority of the bacteria contained 
in the raw water are removed by sedimentation, storage and filtra- 
tion. During the period studied by us the filtered water in the fil- 
tered water reservoirs averaged 36 bacteria per cubic centimeter 
(maximum 80, minimum 13). The water as it runs from the taps 
