the following circumstances: 1. A properly constituted clay, suitable for making a "hard tile," that is, a semivitrified product. 2. The perfect burning of this into properly shaped hard pipes. 3. The laying of these so deeply in the earth, as to protect them from the frost, a most powerfully disturbing and destructive agent. 4. An observance of the proper rules of construction, so as to avoid curves, up and down, to such an extent as to favor the deposition of sand and rubbish, which may find their way into the tiles, through the crevices of the joints. Sand will be arrested at any depressed point in the course of a drain, and clog the conduit so as to prevent the flow of the water. And, last, the protection of the entrance and exit extremities of the pipes, from the admission of small animals, reptiles, and the like, or the treading of cattle. This object can best be attained by the use of tile plates, perforated with fine holes at each end, and inclosing the exit with a fence, or walling it up to prevent the cattle, attracted by the water flowing out, from treading the tiles to pieces. (See page 382.)

In regard to the kind of pipes which are most durable, it may be remarked that "pale," or "soft" tiles are readily softened and broken by the action of the water, while tile may be made perfectly indestructible, if sufficiently burned, by any means save violence, frost, or powerful chemical re-agents, against all of which means of destruction a proper mode of deposit will entirely protect it; and a drain thus constructed, can have no limit assigned to its useful durability. In common phrase, it will last forever."

CHAPTER VIII.

LAYING OUT

DRAINS.

IN laying out drains, the first thing to be determined is the amount of fall. Therefore, the lowest spot on the field or fields to be drained must be selected as the starting point. The amount of fall which can be obtained at the lowest point necessarily determines the depth of the drains. After having determined the amount of fall, the next thing to be determined is, whence comes the water? Should it be ascertained that the water comes from an underground spring, then a drain on the Elkington plan may be advisable. If the water appears in concavity, on the side of a hill, it will, perhaps, be well to examine the soil immediately underneath, and, if an impervious bed underlies, which is in turn succeeded by a porous bed, it may be bored through at short distances, drawing the water into the lower and pervious stratum. Should the water make its appearance at the bottom of the hill, flowing over an impervious stratum, a drain might be dug parallel with the base of the hill, which will remove the water coming from above, and the spring will be cut off. Again, from the bottom of this drain auger holes might be bored through the impervious bed into the next below, should it be found pervious. (See illustration, Fig. 48.)

In this case the purpose is merely to collect and carry off springs that come to the surface-a knowledge of the character and arrangement of the earth a few feet below. the surface, therefore, is very desirable. Where the water washes its way to the surface, in a layer of sand or gravel, lying upon a layer of clay or rock, as is usually the case,

the work is very simple. A ditch or drain is made up to the foot of the hill or ridge, from some creek or other place, where sufficient outfall can be

obtained; it is then carried along the foot of the hill or ridge, usually a little above where the water makes its appearance. The drain must be low enough at the mouth to allow of cutting entirely through the layer of sand or gravel that carries the water, or much will escape under the drain. It is of little use to run drains endwise into banks, for the purpose of drainage, though it is sometimes done successfully when the object is only to obtain a supply of stock water.

In the drainage of swamps, or small basin-like depressions, it is customary to cut a main drain through the center, at a depth sufficient effectually to drain the lowest point. In the direction, for example, from 4 to the top of the hill, 1. Then other drains,

as at 6, 6, 6, 7, which empty into the first from both sides, commencing as near as may be to the edge of the swamp

pressions to a greater or lesser extent, they frequently continue wet and cold, notwithstanding the existence of a good central drain or ditch.

Where there is a basinshaped field, as in the annexed cut (Fig. 50), in which 1 represents a clay soil, 2 a bed of hard-pan, 3, 4 and 5 different layers of rock and shales, 6 gravel, drains may be cut centering at 7, like those at G, G, G, G, in Fig. 51 (next page), at H, cut through the strata into

a pit or well; and, if necessary, minor drains may be cut leading into those figured.

In thorough draining, sufficient fall having been obtained from the lowest point of the land to be drained, that becomes the proper starting point. If the field has a regular descent toward one of its sides, along that side the main drain is carried, and all the minor drains start from and If the lowest part of the land to be thoroughly drained be not along one of its sides, the main drain is carried along the lowest place, whether straight or otherwise, and the minor drains start from it on both sides. If the direction of the minor drains

run parallel one to another.

be at right angles to the main drain, it is better to curve the end of the minor drain for a few feet, where it enters the main, so that its current may not be across that of the main drain, but partly in the same direction.

The fewer main drains and general outlets to a field, the better. In the drainage of hillsides, it has been a question whether the parallel drains should be carried down the line of greatest descent, or obliquely to it; but longer experience has settled the question, where tiles are

FIG. 51.

used, in favor of the line of greatest descent, or, in other words, running the minor drains straight down the slope. One should think that a question apparently so selfevident would require no argument. But we find, in the works of the various writers on this subject, that a great diversity of opinion exists. One party insists that if a drain be cut across the foot of the hill, as at 1, in Fig. 52, it will completely drain not only the stratum 3, but also that indicated by 2, and all above it; and, therefore, object to making drains in the direction of the greatest descent. Another party would make a drain to carry off