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quire a tile nearly five inches in diameter, laid at the given fall, or a 3-inch tile laid at a fall of more than 7 feet in 100 feet. But, again, so much water could not reach a drain four feet from the surface, in so short a time, and the time required would depend very much on the character of the soil. Obviously, then, these tables are worthless for our purpose. Experience has fully shown that the sizes which are recommended below are ample for practical purposes, and probably the areas to be drained by the given sizes might be greatly increased, especially with ref erence to such soils as do not allow water to percolate very freely through them.

In connection with this subject, attention is called to the following extract from the Author's Report on the Drainage, which accompanies the "Third Annual Report of the Board of Commissioners of the Central Park:"

"In order to test the efficiency of the system of drainage "employed on the Park, I have caused daily observations "to be taken of the amount of water discharged from the "principal drain of the Green,' and have compared it with the amount of rain-fall. A portion of the record of those observations is herewith presented.

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"In the column headed 'Rain-Fall,' the amount of 66 water falling on one acre during the entire storm, is given "in gallons. This is computed from the record of a rain "gauge kept on the Park.

"Under the head of 'Discharge,' the number of gallons "of water drained from one acre during 24 hours is given. "This is computed from observations taken, once a day or "oftener, and supposes the discharge during the entire day to be the same as at the time of taking the observa *tions. It is, consequently, but approximately correct:

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"The tract drained by this system, though very swampy "before being drained, is now dry enough to walk upon, 'almost immediately after a storm, except when underlaid "by a stratum of frozen ground."

The area drained by the main at which these gaugings were made, is about ten acres, and, in deference to the prevailing mania for large conduits, it had been laid with 6-inch sole-tile. The greatest recorded discharge in 24 hours was (August 25th,) less than 100,000 gallons from the ten acres,-an amount of water which did not half fill the tile, but which, according to the tables referred to, would have entirely filled it.

In view of all the information that can be gathered on the subject, the following directions are given as per fectly reliable for drains four feet or more in depth, laid on a well regulated fall of even three inches in a hundred feet:

For 2 acres 1 inch pipes (with collars.)

For 8 acres

For 20 acres

For 40 acres 2 31⁄2“

For 50 acres 6

21
31 "

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or one 5-inch sole-tile.
sole-tile.

For 100 acres 8

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or two 6-inch sole-tiles.

It is not pretended that these drains will immediately remove all the water of the heaviest storms, but they will always remove it fast enough for all practical purposes, and, if the pipes are securely laid, the drains will only be benefited by the occasional cleansing they will receive when running "more than full." In illustration of this statement, the following is quoted from a paper communicated by Mr. Parkes to the Royal Agricultural Society of England in 1843:

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"Mr. Thomas Hammond, of Penshurst, (Kent,) now uses no other size for the parallel drains than the inch "tile in the table (No. 5,) having commenced with No.

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"4, and it may be here stated, that the opinion of all the "farmers who have used them in the Weald, is that a bore "of an inch area is abundantly large. A piece of 9 acres, now sown with wheat, was observed by the writer, 36 "hours after the termination of a rain which fell heavily "and incessantly during 12 hours on the 7th of Novem"ber. This field was drained in March, 1842, to the depth "of 30 to 36 inches, at a distance of 24 feet asunder, the "length of each drain being 235 yards.

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"Each drain emptied itself through a fence bank into a running stream in a road below it; the discharge "therefore was distinctly observable. Two or three of "the pipes had now ceased running; and, with the ex"ception of one which tapped a small spring and gave a 66 stream about the size of a tobacco pipe, the run from "the others did not exceed the size of a wheat straw "The greatest flow had been observed by Mr. Hammond at no time to exceed half the bore of the pipes. The "fall in this field is very great, and the drains are laid ir "the direction of the fall, which has always been the prac "tice in this district. The issuing water was transpa "rently clear; and Mr. Hammond states that he has 66 never observed cloudiness, except for a short time after 66 very heavy flushes of rain, when the drains are quickly "cleared of all sediment, in consequence of the velocity "and force of the water passing through so small a channel. "Infiltration through the soil and into the pipes, must. "in this case, be considered to have been perfect; and "their observed action is the more determinate and valua"ble as regards time and effect, as the land was saturated with moisture previous to this particular fall of rain, and the pipes had ceased to run when it commenced This piece had, previous to its drainage, necessarily "been cultivated in narrow stetches, with an open water

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Nɔ 5 was one inch in diameter; No. 4, about 1 inches.

"furrow between them; but it was now laid quite plain, "by which one-eighth of the continuation of acreage has "been saved. Not, however, being confident as to the "soil having already become so porous as to dispense en"tirely with surface drains, Mr. Hammond had drawn "two long water furrows diagonally across the field. On "examining these, it appeared that very little water had flowed along any part of them during these 12 hours of "rain,—no water had escaped at their outfall; the entire body of rain had permeated the mass of the bed, and passed off through the inch pipes; no water perceptible "on the surface, which used to carry it throughout. The "subsoil is a brick clay, but it appears to crack very "rapidly by shrinkage consequent to drainage."

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Obstructions.-The danger that drains will become obstructed, if not properly laid out and properly made, is very great, and the cost of removing the obstructions, (often requiring whole lines to be taken up, washed, and relaid with the extra care that is required in working in old and soft lines,) is often greater than the original cost of the improvement. Consequently, the possibility of tile drains becoming stopped up should be fully considered at the outset, and every precaution should be taken to prevent so disastrous a result.

The principal causes of obstruction are silt, vermin, and roots.

Silt is earth which is washed into the tile with the water of the soil, and which, though it may be carried along in suspension in the water, when the fall is good, will be deposited in the eddies and slack-water, which occur whenever there is a break in the fall, or a defect in the laying of the tile.

When it is practicable to avoid it, no drain should have a decreasing rate of fall as it approaches its outlet.

If the first hundred feet from the upper end of the

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