116 
TYPHOID FEVER IX DISTRICT OF COLE^MBIA. 
THE DEEP WELLS. 
By ^^deep” wells is meant the so-called drilled or ^‘artesian” wells. 
Such wells in the District are rarely less than 100 feet below the mean 
surface level and consist of an iron pipe or tube 6 or 8 inches in diame- 
ter. There are 23 such deep wells used by the public in the District 
of Columbia. Several others, used for institutional, manufacturing, or 
private purposes, were not included in our studies. For the most part, 
the water from these deep wells is of excellent quality, chemically and 
bacteriologically.^ Some of them are practically sterile, and ferment- 
ing organisms are not in evidence. In other words, these deep well 
waters, from a bacteriological standpoint, show the absence of surface 
contamination or sewage pollution. 
The chemical analyses also go to show that these wells furnish water 
of unquestioned purity. In only three instances was the free am- 
monia found to be somewhat higher than the accepted standards. 
SEXIMARY DEEP WELLS. 
Number . — In the following summary the number^’ is the labora- 
tory designation of the well and corresponds for ready reference with 
the same number in the bacteriological and chemical tables. 
Location . — The list of wells in the District was furnished us by the 
health officer. Each well was visited and the location verified. 
Kind . — This refers to the kind of pump, whether wooden or iron. 
Condition . — This refers to‘ the condition of the pump. The base 
and platform in reference to surface contamination are specifically 
noted. Xote is also made in each instance as to whether the waste 
water runs off by surface drainage or runs to the sewer. 
Depth . — Under Depth’’ the first figure is the distance of the bot- 
tom of the tube to the mean surface level ; the second is the height to 
which the water stands in the well, referring to the bottom as zero. 
This data was obtained from the water department of the District of 
Columbia. 
Sewer . — Under ^^Sewer” the figure depth” is the distance of the 
center line of the sewer pipe below the mean surface grade; the figure 
distance from well” is the horizontal distance from the center line 
of the sewer to the approximate center of the well. The depth of 
the sewers was obtained from the sewer department of the District 
of Columbia. The distance of sewers from wells are scaled from 
drawings, and are only roughly approximated. Many of the wells 
seem to be located directly on the line of the sewers. 
Privies .- — -There are about 3,600 privies registered at the health 
office; schools equipped with the Sinead system” being rated as a 
single privy. 
