The second method of distribution, and one more suitable for the conditions under discussion, is to lay out the field in parallel beds from three to six feet wide and from forty to one hundred feet long. These beds are separated by furrows into which the sewage is discharged. If the grade of these furrows is properly adjusted to the porosity of the soil, that is, made about six inches in one hundred feet for open, sandy loam, and about two inches in one hundred feet for fine, clay loam, the soil will absorb the needed moisture as the sewage flows over it and there should be no ponding or excess of water at any point of the field. By dividing the field into three parts, or in arranging the flow of sewage so that it enters only two or three furrows at a time, the flow can be so changed from day to day as to furnish all parts of the area with the irrigating water, and at the same time not overload and choke the soil particles. On the beds may be planted and grown whatever vegetables are desired. A good basis for determining the area and length of furrows required is to provide a length of thirty feet of furrow for each person of the household. The total length thus obtained should not, however, be made continuous, but should be arranged in three parts, or in multiples of three, so that one-third of the total length only may be used on any one day, the other parts serving for other days, so that a rotation is practised. [Illustration: FIG. 48.—Distribution of Sewage and Arrangement of Check Levees on a Hillside.] The third condition involves the application of the sewage to a steep slope, and this may be treated in either one of two ways. The sewage may be led to the top of the hill and allowed to flow, for a short distance only, over the surface on which, presumably, grass is to be grown. If the length of the furrow is more than about a dozen feet, the flowing stream acquires enough velocity to wash the surface and to form gullies. To prevent this, a secondary ditch or small bank is thrown up to arrest the flow. The water is led out again from behind this ditch or bank at intervals, to repeat the process further down the hill (see Fig. 48). If the slope of the ground is moderate, so that there is no tendency of the water to form gullies, the water may be let out of the ditch at intervals and allowed to distribute itself over the field, as shown in Fig. 49. The water thus overflowing should be collected in a drain at the lower end of the slope, and will be found suitably purified for discharge into any running stream not used for drinking purposes. The occasional use of a shovel or hoe may be needed to change the flow of the water over the field if it is found that any tendency exists for definite channels to be formed. [Illustration: FIG. 49.—Distribution of Sewage on a Hillside of Moderate Slope.]