POTOMAC EIVER WATER SUPPLY RELATIVE TO TYPHOID FEVER. 271 
The following is a summary of the number of bacilli present in 1 cc. 
of raw Potomac water, taken from the report of Lieut. Col. A. M. 
Miller, Corps of Engineers, U. S. Army, in Senate Document No. 259, 
Fifty-sixth Congress, first session, 1900: 
Date. 
Maximum. 
Minimum. 
Average. 
Tnlv 09 (lavs') 
1899. 
790 
48 
1 n4 
August 
685 
67 
269 
September 
556 
90 
196 
October 
500 
80 
138 
1 
November 
1,200 
31.000 
51.000 
26,200 
70 
401 
Dpcambpr 
135 
3, 281 
1 700 
.Tap.narv 
1900. 
3, 500 
February 
2,500 
9,950 
Colonel Miller says that — 
The bacteriological results obtained show that the Potomac water as delivered from 
the mains is, in times of turbidity and low temperature, dangerous to health by reason 
of the quantity of bacteria present. 
Fifty per cent of the specimens examined, or one-half, indicated 
the presence of the colon bacillus, from which Colonel Miller concluded 
that the water supply of Washington was dangerous to health and 
required filtration. 
Theobald Smith made a study of the quantitative variations in the 
germ life of Potomac water during the year 1886.® The water for 
these analyses was dravm from a faucet in the basement of the Depart- 
ment of Agriculture which was contantly in use, so there could have 
been no stagnation of the water in the smaller pipes. 
As to the results of these observations, we first observe that the 
number is highest in winter, in spite of the fact that the heat greatly 
favors and cold checks multiplication. 
o Medical News, vol. 50, April 9, 1887, p. 404. 
