Imágenes de páginas
[merged small][ocr errors][graphic][graphic]

for cutting very narrow ditches, only wide enough at the bottom to admit the tile, and not allowing the workmen to stand in the bottom of the ditch. A set of these tools is shown in Fig. 22. Possibly there may be soils in which these implements, in the hands of men skilled in their use, could be employed with economy, but they are very rare, and it is not believed to be possible, under any circumstances, to regulate the bottom of the ditch so accurately as is advisable, unless the workman can stand directly upon it, cutting it more smoothly than he could if the point of his tool were a foot or more below the level on which he stands. On this subject, Mr. J. Bailey Denton, one of the first draining engineers of Great Britain, in a letter to Judge French, says: “As to tools, it is the same with them as it is with the “art of draining itself—too much rule and too much draw“ing upon paper; all very right to begin with, but very “prejudicial to progress. I employ, as engineer to the “General Land Drainage Company, and on my private “account, during the drainage season, as many as 2,000 “men, and it is an actual fact, that not one of them uses “the set of tools figured in print. I have frequently pur“chased a number of sets of the Birmingham tools, and “sent them down on extensive works. The laborers would “purchase a few of the smaller tools, such as Nos. 290, “291, and 301, figured in Morton’s excellent Cyclopædia “of Agriculture, and would try them, and then order “others of the country blacksmith, differing in several “respects; less weighty and much less costly, and more. “over, much better as working tools. All I require of the “cutters, is, that the bottom of the drain should be evenly “cut, to fit the size of the pipe. The rest of the work “takes care of itself; for a good workman will economize “his labor for his own sake, by moving as little earth as “practicable; thus, for instance, a first-class cutter, in “clays, will get down 4 feet with a 12-inch opening, ordi“narily; if he wishes to show off, he will sacrifice his “own comfort to appearance, and will do it with a 10-inch “opening.”

In the Central Park work, sets of these tools were procured, at considerable expense, and every effort was made to compel the men to use them, but it was soon found that, even in the easiest digging, there was a real economy in using, for the first 3 feet of the ditch, the common spade, pick, and shovel,-finishing the bottoms with the narrow spade and scoop hereafter described, and it is probable that the experience of that work will be sustained by that of the country at large.

Marking the Lines.--To lay a drain directly under the position of its stakes, would require that enough earth be left at each point to hold the stake, and that the ditch be tunneled under it. This is expensive and unnecessary. It is better to dig the ditches at one side of the lines of stakes, far enough away for the earth to hold them firmly in their places, but near enough to allow measurements to be taken from the grade pegs. If the ditch be placed always to the right, or always to the left, of the line, and at a uniform distance, the general plan will remain the same, and the lines will be near enough to those marked on the map to be easily found at any future time. In fact, if it be known that the line of tiles is two feet to the right of the position indicated, it will only be necessary, at any time, should it be desired to open an old drain, to measure two feet to the right of the surveyed position to strike the line at once. In soils of ordinary tenacity, ditches 4 feet deep need

not be more than twenty (20) inches wide at the surface, and four (4) inches wide at the bottom. This will allow, in each side, a slope of eight (8) inches, which is sufficient except in very loose soils, and even these may be braced up, if inclined to cave in. There are cases where the soil contains so much running sand, and is so saturated with water, that no precautions will avail to keep up the banks. Ditches in such ground will sometimes fall in, until the excavation reaches a width of 8 or 10 feet. Such instances, however, are very rare, and must be treated as the occasion suggests.

One of the garden lines should be set at a distance of about 6 inches from the row of stakes, and the other at a further distance of 20 inches. If the land is in grass, the position of these lines may be marked with a spade, and they may be removed at once; but, if it is arable land, it will be best to leave the lines in position until the ditch is excavated to a sufficient depth to mark it clearly. Indeed, it will be well to at once remove all of the sod and surface soil, say to a depth of 6 inches, (throwing this on the same side with the stakes, and back of them.) The whole force can be profitably employed in this work, until all of the ditches to be dug are scored to this depth over the entire tract to be drained, except in swamps which are still too wet for this work.

Water Courses.—The brooks which carry the water from the springs should be “jumped ” in marking out the lines, as it is desirable that their water be kept in separate channels, so far as possible, until the tiles are ready to receive it, as, if allowed to run in the open ditches, it would undermine the banks and keep the bottom too soft for sound work.

With this object, commence at the southern boundary of our example tract, 10 or 15 feet east of the point of outlet, and drive a straight, temporary, shallow ditch to a point a little west of the intersection of the main line D with its first lateral; then carry it in a northwesterly direction, crossing C midway between the silt-basin and stake C 1, and thence into the present line of the brook, turning all of the water into the ditch. A branch of this

ditch may be run up between the lines Fand G to receive the water from the spring which lies in that direction. This arrangement will keep the water out of the way until the drains are ready to take it. The Outlet,_The water being all discharged through the new temporary ditch, the old brook, beyond the boundary, should be cleared out to the final level (3.75,) and an excavation made, just within the boundary, sufficient to receive the masonry which is to protect the outlet. A good form of outlet is shown in Fig. 23. It may


be cheaply made by any farmer, especially if he have good stone at hand;—if not, brick may be used, laid on a solid foundation of stout planks, which, (being protected from the air and always saturated with water,) will last a very long time. If made of stone, a solid floor, at least 2 feet square, should be placed at, or below, the level of the brook. If this consist of a single stone, it will be better than if of several smaller pieces. On this, place another layer extending the whole width of the first, but reaching only from its inner edge to its center line, so as to leave a foot

« AnteriorContinuar »