I have had forwarded to me during the past year many samples of well water from different sections of the state for examination, and _over ninety-five per cent. were contaminated_. In many instances no particular suspicion existed that the wells were polluted, so “sweet and sparkling” was the water. With the exception of a few wells in this city, the samples came from the smaller villages and isolated farm-houses. I suspect, and my experience is in accord with the idea, that the most dangerous wells are to be found at the latter, because such a well is subjected not only to the unsanitary influences of the household, but of the barns, cattle-yards, hennery, pig-sty, etc. No one can reasonably presume that a well situated in close proximity to such surroundings can long remain pure, except that its altitude is such as to render contamination impossible, which is rarely the case. It should be borne in mind that a well is in itself a system of drainage for a given area of the earth, which area is dependent upon the depth of the well and the character of the soil. The accepted formula is, that it drains a portion of soil represented by an inverted cone, the base of which equals in diameter the depth of the well. Thus, the well _must_ drain a certain amount of soil or earth, and unless this certain amount is kept clean and uncontaminated, the well _must become polluted_. It should not be forgotten that this described cone of soil is the _minimum_ amount that a well can drain, while with favorable conditions the maximum area is almost unlimited. A stratum of clay or other impervious substance, or fissures in the rock formation, may act as the carrier of a little stream or vein of polluted water till it reaches the well, and the source of pollution may be a long distance away. The sketch which is here reproduced from the last report of the State Board of Health vividly illustrates the way in which a well is often polluted. [Illustration]