« AnteriorContinuar »
"may seem curious to our experiences, in these days, that "such a doctrine could ever have needed to be enforced "by argument; yet no one will deem it wonderful who
has personally witnessed the unaccountable and ever new "difficulty of getting proper attention paid to the leveling "of the bottom of a drain, and the laying of the tiles in "that continuous line, where one single depression or ir"regularity, by collecting the water at that spot, year "after year, tends toward the eventual stoppage of the M whole drain, through two distinct causes, the softening "of the foundation underneath the sole, or tile flange, and "the deposit of soil inside the tile from the water collected "at the spot, and standing there after the rest had run off. "Every depression, however slight, is constantly doing "this mischief in every drain where the fall is but trifling; "and if to the two consequences above mentioned, we "may add the decomposition of the tile itself by the "action of water long stagnant within it, we may deduce "that every tile-drain laid with these imperfections in "the finishing of the bottom, has a tendency toward "obliteration, out of all reasonable proportion with "that of a well-burnt tile laid on a perfectly even inclina"tion, which, humanly speaking, may be called a penna*' nent thing. An open ditch cut by the most skillful "workman, in the summer, affords the best illustration of "this underground mischief. Nothing can look smoother "and more even than the bottom, until that uncompromis"ing test of accurate levels, the water, makes its appear"ance: all on a sudden the whole scene is changed, the "eye-accredited level vanishes as if some earthquake had "taken place: here, there is a gravelly scour, along which "the stream rushes in a thousand little angry-looking rip"pies; there, it hangs and looks as dull and heavy as if it
had given up running at all, as a useless waste of energj; "in another place, a few dead leaves or sticks, or a morsel "of soil broken from the side, dams back the water for a
considerable distance, occasioning a deposit if soil along "the whole reach, greater in proportion to the quantity ■ and the muddiness of the water detained. All this shows "the paramount importance of perfect evenness in the "bed on which the tiles are laid. The worst laid tile is "the measure of the goodness and permanence of the "whole drain, just as the weakest link of a chain is the u measure of its strength."
The simple laying of the smaller sizes of pipes and collars in the- lateral drains, is an easy matter. It requires care and precision in placing the collar equally under the end of each pipe, (having the joint at the middle of the collar,) in having the ends of the pipes actually touch each other within the collars, and in brushing away any loose dirt which may have fallen on the spot on which the collar is to rest. The connection of the laterals with the mains, the laying of the larger sizes of tiles so as to form a close joint, the wedging of these larger tiles firmly into their places, and the trimming which is necessary in going around sharp curves, and in putting in the shorter pieces which are needed to fill out the exact length of the drain, demand more skill and judgment than are often found in the common ditcher. Still, any clever workman, who has a careful habit, may easily be taught all that is necessary; and until he is thoroughly taught,—and not only knows how to do the work well, but, also, understands the importance of doing it well,—the proprietor should carefully watch the laying of every piece.
Never have tiles laid by the rod, but always by the day. "The more haste, the less speed," is a maxim which applies especially to tile-laying.
If the proprietor or the engineer does not overlook the laying of each tile as it is done, and probably he will not, lie should carefully inspect every piece before it is covered. It is well to walk along the ditches and touch each tile with the end of a light rod, in such a way as to see whether it is firm enough in its position not to be displaced by the earth which will fall upon it in filling the ditches.
Preparatory to laying, the tiles should be placed along one side of the ditch, near enough to be easily reached by a man standing in it. When collars are to be used, one of these should be slipped over one end of each tile. The workman stands in the ditch, with his face toward its upper end. The first tile is laid with a collar on its lower end, and the collar is drawn one-half of its length forward, so as to receive the end of the next tile. The upper end of the first tile is closed with a stone, or a bit of broken tile placed firmly against it. The next tile has its nose placed into the projecting half of the collar of the first one, and its own collar is drawn forward to receive the end of the third, and thus to the end of the drain, the workman walking backward as the work progresses. By and by, when he comes to connect the lateral with the main, he may find that a short piece of tile is needed to complete the length; this should not be placed next to the tile of the main, where it is raised above the bottom of the ditch, but two or three lengths back, leaving the connection with the main to be made with a tile of full length. If the piece to be inserted is only two or three inches long, it may be omitted, and the space covered by using a whole 2£-inch tile in place of the collar. In turning corners or sharp curves, the end of the tile may be chipped off, so as to be a little thinner on one side, which will allow it to be turned at a greater angle in the collar.
If the drain turns a right angle, it will be better to dig out the bottom of the ditch to a depth of about eight inches, and to set a 6-inch tile on end in the hole, perforating its sides, so as to admit the ends of the pipes at the proper level. This 6-inch tile, (which acts as a small silt-basin,) should stand on a board or on a flat stone, and its top should be covered with a stone or with a couple nl "bricks. Wood will last almost forever below the level of the drain, where it will always be saturated with water, but in the drier earth above the tile, it would be quite jure to decay.
The trimming and perforating of the tile is done with a "tile-pick," (Fig. 32,) the hatchet end, tolerably sharp, being used for the trimming, and the point, for making the holes. This is done by striking lightly around the circumference of the hole until the center piece falls in, or can easily be knocked in. If the hole is irregular, and does not fit the
Fig. 32.-^ick For tile nicelv, the °Pen sPate should be Dressing And Per- covered with bits of broken tile, to
PORATING TILE. i .1 .1
keep the earth out.
As fast as the laterals are laid and inspected, they should be filled in to the depth of at least a foot, to protect the tile.; from being broken by the falling of stones or lumps of earth from the top, and from being displaced by water flowing in the ditch. Two or three feet of the lower end may be left uncovered until the connection with the main is finished.
In the main drains, when the tiles are of the size with which collars are used, the laying is done in the same manner. If it is necessary to use 3^-inch tiles, or any larger size, much more care must be given to the closing of the joints. All tiles, in manufacture, dry more rapidly at the top, which is more exposed to the air, than at the bottom, and they are, therefore, contracted and made shorter at the top. This difference is most apparent in the larger sizes. The large round tiles, which can be laid on any side, can easily be made to form a close joint, and they should be secured in their proper position by stones or lumps of earth, wedged in between them and the sides of the ditch. The sole tiles must lie with the shortest sides np, and usually, the space between two tiles, at the Unp, will be from one-quarter to one-half of an inch To remedy this defect, and form a joint which may be protected against the entrance of earth, the bottom should be trimmed off, so as to allow the tops to come closer to gether. Any opening, of less than a quarter of an inch can be satisfactorily covered,—more than that should not be allowed. In turning corners, or in passing around curves, with large tiles, their ends must be beveled off with the pick, so as to fit nicely in this position.
The best covering for the joints of tiles which are laid without collars, is a scrap of tin, bent so as to fit their shape,—scraps of leather, or bits of strong wood shavings, answer a very good purpose, though both of these latter require to be held in place by putting a little earth over their ends as soon as laid on the tile. Very small grass ropes drawn over the joints, (the ends being held down with stones or earth,) form a satisfactory covering, but care should be taken that they be not too thick. Strips of newspaper, doubled and laid over the joints, answer an excellent purpose. Care, however, should always be taken, in using any material which will decay readily, to have no more than is necessary to keep the earth out, lest, in its decay, it furnish material to be carried into the tile and obstruct the flow. This precaution becomes less necessary in the case of drains which always carry considerable streams of water, but if they are at times sluggish in their flow, too much care cannot be given to keep them free of all possible causes of obstruction. As nothing is gained by increasing the quantity of loose covering beyond what is needed to close the joints, and as such covering is only procured with some trouble, there is no reason for its extravagant use.
There seems to remain in the minds of many writers on drainage a glimmering of the old fallacy that underdraint, like open drains, receive their water from above, and it if