In Fig. 148 is shown a larger and more complete plant than the former, in which a windmill furnishes the power for pumping and a large underground tank is utilized for the main supply of water. The tank marked, Well Water Pressure Tank, in this case is so placed that the end is exposed in the well curb, where the height of the water may be observed at any time. The pump is operated as any other of its kind, but is provided with an automatic pressure cylinder, which controls the operation of the mill through the rise and fall of the water in the tank. At any time the water in the tank falls to a certain point, the pump is thrown into gear by the pressure cylinder, and the water is pumped into the tank until a definite height is reached; at this point the pump is automatically thrown out of gear and remains inactive until an additional supply of water is required. The plant is therefore automatic in its action and requires only that the mill be kept oiled and in running order.

Fig. 147. - Pressure tank supplied by an electrically driven pump.

As shown in the drawing, the large tank receives its supply of water from the well and aside from providing a reserve supply furnishes power for pumping cistern water. The water from the large tank is piped into the house for use as required, and from the same pipe is taken a hydrant for lawn sprinkling; in addition, this water is piped to the barn where it is used for watering stock. A branch of the same pipe is intended to operate a water lift, which in turn furnishes the house with soft water from the rainwater cistern for bathing, laundry, and kitchen purposes.

Fig. 148. - This diagram shows the arrangement of domestic water-supply-apparatus, in which a windmill furnishes the pressure necessary for operating the entire plant.