“All authorities agree that any well situated within a few feet of a cess-pool or sewer should be regarded with grave suspicion, for the intervening soil may become overdone with filth at any moment, and cease to act as an efficient filter of the polluted water, and allow organic matter to enter the well; or animal filth may be washed into the well at any time by a hard rain.” A great many citizens of Indianapolis are drinking water exclusively from cisterns. It is difficult to estimate the number of cisterns within the city limits; but a great deal may be said in regard to the general unwholesomeness of the water they contain. Rain water contains a small proportion of chlorine, the amount varying with the condition of the atmosphere, and the purity of the shedding surface. When pure rain falls upon a roof it carries down with it all the impurities accumulated there during dry weather; these soon putrify in the cistern, and infect the water. The majority of the cisterns in the city are faulty in some particular—either proper care was not exercised in their construction, or the necessary repairs were not made in due time—and they are found to be seeping, or leaky. Sufficient attention is not given to keeping the cisterns well closed, and the result is that filth in large quantities is to be found on emptying them. During my examinations I have met with many cistern waters in the city so polluted by sewage infiltration, that an immediate interdict on their use appeared to be called for. Owing to the impurity of the soil, sewage matter finds its way into hundreds of cisterns, and contaminates the water. Many of our cisterns contain water rank with vegetable or animal impurity, and the contents of the greater portion of these are not above suspicion. Some of them are neither more or less than shallow wells, receiving more of their contents by percolation than by inflow above. Last December 458 cisterns in Memphis, Tenn., were examined with the following result: Sound, 209; seeping, eighty-two; and undoubtedly leaking, 167. In the total number, there were 249 condemned as unfit for use. To what extent these leaky cisterns contributed to the epidemic of yellow fever we cannot tell. The probability of sewage contamination in each instance was strong.