of disease, and these gain the upper hand under the altered conditions of city and business life.  It is not too much to say that every man and woman should know the source of his summer table water and the method of sewage disposal.  If the conditions are unsanitary, they cannot be remedied at once, but another resort can be found and personal danger can be avoided.  Public sentiment and the loss of trade will go far in furthering an effort toward better sanitation.

In the driven well, water cannot reach the spout unless it has first filtered through the soil to the depth of the driven pipe; after such a journey it is fairly safe, unless very large quantities of sewage are present; generally speaking, such a depth of soil is able to filter satisfactorily the drainage of the limited number of people which a driven well suffices to supply.

[Illustration:  FIG. 141.—­A deep well with the piston in the water.]

Abundant water is rarely reached at less than 75 feet, and it would usually be impossible to drive a pipe to such a depth.  When a large quantity of water is desired, strong machines drill into the ground and excavate an opening into which a wide pipe can be lowered.  I recently spent a summer in the Pocono Mountains and saw such a well completed.  The machine drilled to a depth of 250 feet before much water was reached and to over 300 feet before a flow was obtained sufficient to satisfy the owner.  The water thus obtained was to be the sole water supply of a hotel accommodating 150 persons; the proprietor calculated that the requirements of his guests, for bath, toilet, laundry, kitchen, etc., and the domestics employed to serve them, together with the livery at their disposal, demanded a flow of 10 gallons per minute.  The ground was full of rock and difficult to penetrate, and it required 6 weeks of constant work for two skilled men to drill the opening, lower the suction pipe, and install the pump, the cost being approximately $700.

[Illustration:  FIG. 142.—­Showing how drinking water can be contaminated from cesspool (c) and wash water (w).]

The water from such a well is safe and pure except under the conditions represented in Figure 142.  If sewage or slops be poured upon the ground in the neighborhood of the well, the liquid will seep through the ground and some may make its way into the pump before it has been purified by the earth.  The impure liquid will thus contaminate the otherwise pure water and will render it decidedly harmful.  For absolute safety the sewage discharge should be at least 75 feet from the well, and in large hotels, where there is necessarily a large quantity of sewage, the distance should be much greater.  As the sewage seeps through the ground it loses its impurities, but the quantity of earth required to purify it depends upon its abundance; a small depth of soil cannot take care of an indefinite amount of sewage.  Hence, the greater the number of people in a hotel, or the more abundant the sewage, the greater should be the distance between well and sewer.