Rural Hygiene

by Henry N. Ogden

Second, a gravity supply is to be preferred because of its greater reliability. It is hardly possible to imagine any excuse for a gravity supply failing to deliver its predetermined quantity of water regularly day after day. A pumping plant, on the other hand, both breaks down and wears out. Valves are continually requiring to be repacked, nuts drop off and have to be replaced, pieces of the machinery break and require repairs, so that with the best machinery it is almost inevitable that for many days in the year the water-supply is interrupted by some failure of the machinery. In planning water works for cities, an engineer weighs and estimates the value of a continuous service, and even if the gravity supply costs somewhat more than the pumping system, it is in many cases adopted because the greater cost is supposed to be compensated for by the greater reliability of the supply.

Windmills.

Perhaps the cheapest source of power for pumping water is a windmill, and in many cases it proves entirely serviceable. It has two drawbacks which are self-evident. Unless the wind blows, the mill will not work, and, unfortunately, at those times of the year when a large supply of water is most to be desired, that is, during the hot summer months, the wind is particularly light. It is necessary, therefore, when using wind as a source of power, to provide large storage which will tide over the intervals between the times of pumping. Again, the wind may blow frequently enough, but may be so light as not to turn the large vanes necessary to pump rapidly and easily the large amount of water needed. Nothing less than a twelve-foot mill ought to be erected, and, to be efficient, the wind must blow at the rate of twelve to sixteen miles an hour.

Fig. 43.—Windmill and water tank.

A windmill of the best design is made entirely of steel with small angle irons for posts for the tower, and with the mill itself made of galvanized iron. It requires a good foundation and must be well anchored to the masonry piers by strong bolts set well down into the masonry. If the mill is set directly over the well and the storage tank supported on the tower, a very compact arrangement is accomplished and the danger from frost is the only difficulty to be apprehended. However, the tank is often placed in the attic, some distance from the well, to which it is connected by suitable piping.

The location of the windmill requires careful consideration in order that it may receive the prevailing winds in their full force and at the same time be properly located with reference to the well. It must be remembered that the surface of the wheel is exposed to the full fury of a storm, and both the wheel and the tower must be strong enough to withstand such storms. Figure 43 shows windmill and water tank in the vicinity of Ithaca, New York.

Hydraulic rams.

A hydraulic ram is the cheapest method of pumping water, provided that the necessary flow with a sufficient head to do the work is available. It requires about seven times as much water to flow through the ram and be wasted as is pumped, so that if it is desired to pump five hundred gallons a day, the stream must flow at the rate of about thirty-five hundred gallons per day to lift the necessary water.

The two disadvantages of a ram are, first, that a fall of water is not always obtainable or that the stream flow is not always sufficient, and second, that the action of the ram is subject to interruptions on account of the accumulation of air in summer and on account of the formation of ice in winter. In fact, in winter it is necessary to keep a small fire going in the house where the ram is at work in order that this interruption may not take place. Its great advantage is that it requires no attendance, no expense for maintenance, and practically nothing for repairs. It operates continuously when once started, and, except for the occasional interruption on account of air-lock, is always on duty.