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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 end wise into banks, for the purpose of drainage, though it is sometimes done successfully when the object is only to obtain a supply of stock

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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 bill, 1. Then other drains, as at 6, 6, 6, 7, which empty into the first from both sides, com. mencing as near as may be to the edge of the swamp to catch the water in its descent from the higher lands. Without these side drains, or a drain encircling such depressions 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 basin-shaped field, as in the annexed cut (Fig. 39), in which

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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. 40 (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 run parallel one to another. 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, 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 billsides, it has been a question whether the parallel drains should be carried down

FIG 40.

the lines of greatest descent, or obliquely to it; but longer experience has settled the question, where the tiles are 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 self-evident 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 41, it will completely drain not only the stra

FIG. 41.

tum 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 the water from each stratum which would crop out

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 end wise into banks, for the purpose of drainage, though it is sometimes done successfully when the object is only to obtain a supply of stock

[merged small][graphic][merged small]

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 bill, 1. Then other drains, as at 6, 6, 6, 7, which empty into the first from both sides, com. mencing as near as may be to the edge of the swamp to catch the water in its descent from the higher lands. Without these side drains, or a drain encircling such depressions 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 basin-shaped field, as in the annexed cut (Fig. 39), in which

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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. 40 (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 run parallel one to another. 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, 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

FIG 40.

the lines of greatest descent, or obliquely to it; but longer experience has settled the question, where the tiles are 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 self-evident 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 41, it will completely drain not only the stra

FIG. 41.

tum 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 the water from each stratum which would crop out

from the hillside. But, in order to drain land effectually, it is essentially necessary that we have a correct idea of the sources from which the water is derived that is to be carried off; whether the water is directly from the clouds, or is derived from fields enjoying a greater elevation, and sloping toward it, so that the water comes down, like on a roof, from the other fields; or whether it comes up in springs, which find vent in particular spots, as indicated at 7, Fig. 38. If the water is not derived from the adjoining fields but from the clouds direct, a different mode of draining is required than would be if the water came from higher fields. When lands are situated midway on an undrained slope, from which the water spreads over the surface of the land, such a system must be adopted as will not only drain the field in question, but also to cut off the supply of water from the higher fields.

One thing must be borne in mind, that water runs down hill, and does not run so as to spread laterally. From the fact that water always seeks the lowest level by force of gravitation, and drains are simply lower levels to conduct the surplus water away, in order to decide correctly what direction a drain should have, it is not only necessary to have a correct idea of the sources of water, and the superposition of strata, but a definite idea as to the special office the drain is to perform so as to carry off the surplus water and drain the land.

As before stated, drains should be dug up and down the slope, as from 1 to 2, Fig. 41. Suppose a man has a field lying on a slope, which he wishes to drain. If he lay out his drains thirty feet apart, and cut them up and down the line of greatest descent, it is very evident that the drains will then intersect all the strata, and bear away the water from all of them. But, if he lay out his drains the same distance apart across the line of greatest descent, the lower drain will receive the water from the thirty feet next above it; the next drain from the thirty feet next above that and so on; thus compelling the water to traverse or percolate through thirty feet of soil before reaching a drain. But in the other case, the water will traverse a distance of fifteen feet only to find a conduit. The line of the greatest fall is the only line in which the drain is relatively lower than the land on either side of it. The water must be disposed of which rests upon the impervious strata, whether it has found its way there from fields or strata above, or whether it is water from the clouds, and has recently found its way there. But, in order to drain a field lying on a slope, with higher lands above it, it is, perhaps, as well to cut the upper drain across the line of greatest descent, and lead it, as a sub-main, down the line of greatest descent, at the side or center of the field, to the outlet. This answers the purpose, as these drains significantly have been termed, of mere catch-waters.

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