Much more favorable results may be expected, of course, during the warmer weather. The intention was to ascertain, the conditions at about the most unfavorable season. Fig. 1 is reproduced from a photograph of the filter beds taken at the time. The method of sewage disposal by sub surface irrigation (which is but a form of intermittent filtration) is applicable in so many instances that a more detailed statement of the process may be of interest. The object sought is the intermittent distribution of the sewage immediately beneath the surface, preferably of lawns or other grassed areas. The purification at this point being as previously stated, most rapid and giving no offense to the senses. The requisite appliances are the following: A water tight tank or chamber to receive the sewage and from which it may be discharged at intervals and a network of agricultural tiles laid beneath the surface with open joints through which the sewage may exude. Practice indicates that as the sewage comes from the house it should first pass into a small catch basin or chamber adapted to intercept the solid matters and grease from sinks, etc., passing from this into the tank proper from which it is discharged either by hand or automatically. The general arrangement of the system is shown in Fig. 2. From the collecting tank the sewage passes through a pipe with impervious joints to the irrigation field which may, if the conditions are favorable, be within 25 or 50 feet for single houses. The distributing pipes are of small diameter and should be laid about eight or ten inches deep. They should have a slight fall which is secured by laying them on lines closely conforming with the contours. Special appliances are now manufactured for use in this system which serve to perfect the details, but the system may be constructed from materials which can be bought in almost any town. The system as above described contemplates the disposal of solid matters from water closets and other matter usually discharged into sewers. Where applied to the disposal of liquid waste only as in connection with a system of earth closets it may be somewhat simplified. Fig. 2 shows the collecting tank fitted up with an automatic syphon by which the sewage is discharged at proper intervals without attention, a very desirable feature. The ordinary round agricultural tiles laid in special gutter pieces and covered at the joints with special caps to exclude the earth are generally used. The Y branches are designed to permit the escape of sewage completely from the main lines. A very good substitute may be made from common material as shown in Fig. 3. Take ordinary hard burned bricks and lay end to end on the proper grade and at the proper depth. On these lay, as shown in the photograph, alternately, tiles of different diameter, inserting the ends of the smaller tiles in the ends of the larger. The larger tiles will thus serve the purpose of both the gutter and cover plates and the sewage will escape through the space represented by the difference in diameter of the pipes. If after some years it becomes necessary to take up the tiles and clean them the brick foundation need not be disturbed and the tiles can be replaced in their former position with little trouble. Although it is usual when water closet wastes are admitted to provide for the interception of the particles having a tendency to clog the distribution drains there will be but a slight accumulation in the intercepting chamber. The solid matter will by decomposition become so thoroughly macerated and dissolved that it will pass off in solution or in the form of small particles in suspension with the liquid. The comparatively small size of the intercepting chamber as compared with the quantity of sewage passing through it daily will prevent its contents from becoming offensive, especially as the chamber is set below the ground. In the case of a single cottage where earth closets are used the intercepting chamber and collecting chamber are sometimes dispensed with, which materially reduces the cost of the system. Compact soils should be thoroughly under-drained to make them suitable for subsurface disposal. In the case of sandy or gravelly soils it is not necessary. It is a significant fact that in the case of porous subsoils overlaid by loamy soils which are less pervious, a greater quantity of sewage may be purified by this method than by application to the surface over the entire area. In an experiment detailed in the report cf the Massachusetts board of health before referred to, it was found that three times the quantity could be applied by this method with equal results. The length of tile drains necessary to dispose of the sewage by this method varies from 50 to 200 feet for each person and in open, sandy soils, where the sewage from a large number of persons is contributed it may be less. This is on the basis of 50 to 100 gallons of sewage for each person daily. Ordinary residences properly fitted with modern plumbing and fixtures so that there is no extravagant waste of water will be amply served by 25 to 50 gallons. The distributing tiles may be laid in lines about four or five feet apart so that the area necessary to serve as the irrigation field will be 250 to 500 square feet for each person. It is apparent therefore, that the ordinary urban lot of 4x8 rods with the area of lawn usually found in the smaller cities of this state will be sufficient for the purification of the sewage of the occupants. And that the area usually found convenient to |