A method of surmounting this difficulty is seen in Fig. 229. This consists in the use of a standpipe, open at the top, connected with the drive pipe at or near the point where the latter changes its direction. The water will stand in this pipe when the ram has been connected, at the same level as the water in the spring. It is the standpipe, then, that operates the drive rather than the spring, its advantage being in making the drive more direct.

Under some conditions it may be more advantageous to use a tank instead of a standpipe, the result being the same.

In Fig. 230 is shown a full-page illustration of a system of

FIG. 229.-Method of Obtaining Direct Drive for Hydraulic Ram.

plumbing, drainage, and supply, for a small country home. No venting is shown, the fixtures having separate entrances into the stack, and so planned that there will be the least possible danger from siphonage.

This illustrates the common, and it may be called the old-style method of providing a pressure supply. The reader can see clearly the advantages that would be gained in this work by the use of the modern apparatus previously described.

It has not been the aim of the author in this chapter to give anything but a brief description of the several devices described and illustrated.

FIG. 230.-System of Drainage and Supply for a Country House.

However, a comprehensive treatment of each of these subjects, both from a theoretical and from a practical standpoint, will be found in the author's work entitled "Modern Plumbing Illustrated."

It may be added, by the way, that the subject of cesspools and the disposal of country sewage onto filter beds and into underground irrigating systems will be found elsewhere in this work.

The water lift, a device which is generally looked upon as one which has an application only to city work, is coming more and more into use in connection with country plumbing systems, and in many instances it will be found of great advantage. The action and description of the water lift will be found elsewhere in this work. Briefly, however, its action may be said to be that of the steam engine with water pressure as the motive power instead of steam pressure.

Fig. 231 shows an application of the water lift to the country plumbing system. In the absence of any street pressure, the water lift is operated by tank pressure. As the water used in running the water lift is of small amount, the demand on the tank is not great.

By means of the use of a compression tank, the lift delivers water to the fixtures under pressure. The tank operates by the compression of the air within it, and its proper position is at some point between the fixtures and the lift.

By means of the bibb on the suction pipe, the air in the tank may be renewed at any time. By opening the bibb slightly, air will be drawn in through it as the lift draws on the suction.

The cross-connection on the lift, as shown in the illustration, will allow the supply to fixtures of water from the tank whenever the well or cistern supply becomes exhausted. The use of the water lift in connection with country work is of special advantage when the supply of soft water is limited, and it is desired to use the hard well water as far as possible, or when it is desired to supply the house with soft water from cisterns and operate the lift with hard water pumped into the attic tank.

*"Modern Plumbing Illustrated," by R. M. Starbuck, is published by The Norman W. Henley Publishing Co., 132 Nassau Street, New York. Price $4.

FIG. 231.-The Use of the Water Lift in Connection with the Country Plumbing

System.

CHAPTER XXI

FILTRATION OF SEWAGE AND WATER SUPPLY

THE subject of filtration, and the action, construction, and connection of filters should be thoroughly understood by the plumber and by the architect as well.

At first thought this subject may seem to be somewhat outside of the plumber's province, but this is not true, for it is a matter which is very often associated with the procuring of a pure water supply, and also with the proper disposal of sewage. The filtration of water supplies is a matter more especially pertaining to city work, while the filtration of sewage, as taken up in this work, applies chiefly to country work, or at least to those plumbing systems which have not the advantage of disposal into a public sewage system.

Filtration depends upon the action of certain forms of bacteria, which attack the impurities of the water or sewage, reducing them. to other and purer forms. In the purification of drinking water, the action is ordinarily performed by bacteria which exist in countless numbers in sand, charcoal, stone, and various other porous substances. This form of bacteria depends entirely upon the presence of oxygen for the performance of their work. In the purification of sewage, however, it must first come under the action of an entirely different class of bacteria, which exist in vast numbers in the sewage itself, and which multiply enormously in tanks or other receptacles for sewage, when arranged in proper manner.

These bacteria have the ability to reduce animal and vegetable matter to liquids. These liquids are then further purified in the manner described above, the two purifying processes enabling the transformation of sewage into water of such purity that it may be used as drinking water with perfect safety.

In the purification of water supplies there are two methods of filtration, that by pressure and that by gravity. The former clari