IOWA ACADEMY OF SCIENCE 
139 
of only .62 cases of typhoid per year among them, and, of course, 
most of these residents are remote from the stream. 
“Figuring it in another form, and assuming the domicile in as 
close proximity to the stream as the track : A resident population 
0 f 2X1 ,ooo = 32 persons would produce the same chance of 
50X 1 • 24 
infection that will be presented by 1,000 passengers per day on 
the trains.” 
Mr. Alvord, in a final discussion of this problem, summarizes 
the following: 
“I. That in the Cedar River watershed the city of Seattle 
possesses a magnificent source of water supply. 
“II. That the city is not now and has not in the last few years 
properly protected this area from gross pollution now existent. 
“III. That a virgin forest or inaccessible country does not af- 
ford ideal protection from pollution, but, on the contrary, a district 
easily accessible in every part and open to the publicity of fre- 
quent inspections and control offers the greatest degree of pro- 
tection. 
“IV. It is the settled policy, therefore, of most sanitary control 
of watersheds, while preventing as far as possible the growth of 
population and the incidental pollution therefrom, to open water- 
sheds freely to the public observation, by creating means of access 
which facilitate inspection. 
“V. Railroads, so far as the track and trains are concerned, are 
not regarded as a menace to the purity of surface waters by sani- 
tary authorities. 
“VI. It is through population and industries created by rail- 
roads that sanitary difficulties occur. 
“VII. The twenty-five miles or so of railway now existing in the 
Cedar River watershed are in themselves no menace to the valley, 
but the logging camps which they serve are so conducted as to be 
serious pollutions in many cases. 
“VIII. That the operation of a completed railway line by the 
Chicago, Milwaukee & St. Paul Railway Company on or near the 
present location can be made entirely safe by some simple precau- 
tions, .such as fencing, drainage, closed bridge floors and locked 
water closets. 
“IX. That care should be exercised during the period of con- 
struction of the railroad to prevent all access to the water by men 
or animals. For this purpose the river front should be entirely 
