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So far as tile drains are concerned, if they are once well laid, and if the silt-basins have been emptied of silt until the water has ceased to deposit it, they need no care nor attention, beyond an occasional cleaning of the outlet brook. Now and then, from the proximity of willows, or thrifty, young, water-loving trees, a drain will be obstructed by roots; or, during the first few years after the work is finished, some weak point,-a badly laid tile, a loosely fitted connection between the lateral and a main, or an accumulation of silt coming from an undetected and persistent vein of quicksand,—will be developed, and repairs will have to be made. Except for the slight danger from roots, which must always be guarded against to the extent of allowing no young trees of the dangerous class to grow near a drain through which a constant stream of water flows, it may be fairly assumed that drains which have been kept in order for four or five years have passed the danger of interruption from any cause, and they may be considered entirely safe.

A drain will often, for some pionths after it is laid, run rauddy water after rains. Sometimes the early deposit of silt will nearly fill the tile, and it will take the water of several storms to wash it out. If the tiles have been laid in packed clay, they cannot long receive silt from without, and that which makes the flow turbid, may be assumed te. come from the original deposit in the conduit. Examinations of newly laid drains have developed many instances where tiles were at first half filled with silt, and three: months later were entirely clean. The muddiness of the flow indicates what the doctors call “ an effort of nature to relieve herself,” and nature may be trusted to succeed, at least, until she abandons the effort. If we are sure that a drain has been well laid, we need feel no anxiety because it fails to take the water from the ground so completely as it should do, until it settles into a flow of clear water after the heaviest storms.

In the case of an actual stoppage, which will generally bé indicated by the “bursting out” of the drain, i. e., the wetting of the land as though there were a spring under it, or as though its water had no underground outlet, (which is the fact, it will be necessary to lay open the drain until the obstruction is found.

In this work, the real value of the map will be shown, by the facility which it offers for finding any point of any line of drains, and the exact locality of the junctions with the mains, and of the silt-basins. In laying out the plan on the ground, and in making his map, the surveyor will have had recourse to two or more fixed points; one of them, in our example, (fig. 21,) would probably be the center of the main silt-basin, and one, a drilled hole or other mark on the rock at the north side of the field. By staking out on the ground the straight line connecting these two points, and drawing a corresponding line on the map, we shall have a base-line, from which it will be easy, by perpendicular offsets, to determine on the ground any peint upon the map. By laying a small square on the map, with one of its edges coinciding with the base-line, and moving it on this line until the other edge meets the

desired point, we fix, at the angle of the square, the point on the base-line from which we are to measure the length of the offset. The next step is to find, (by the scale,) the distance of this point from the nearest end of the base-, line, and from the point sought. Then measure off, in tha field, the corresponding distance on the base-line, and, from the point thus found, measure on a line perpendicular to the base line, the length of the offset; the point thus indicated will be the locality sought. In the same manner, find another point on the same drain, to give the range on which to stake it out. From this line, the drains which run parallel to it, can easily be found, or it may be used as a base-line, from which, by measuring offsets, to find other points near it.

The object of this staking is, to find, in an inexpensive and easy way, the precise position of the drains, for which it would be otherwise necessary to grope in the dark, verifying our guesses by digging four-foot trenches, at random.

If there is a silt-basin, or a junction a short distance beow the point where the water shows itself, this will be the best place to dig. If it is a silt-basin, we shall probably find that this has filled up with dirt, and has stopped the flow. In this case it should be cleaned out, and a point of the drain ten feet below it examined. If this is found to be clear, a long, stout wire may be pushed up as far as the basin and worked back and forth until the passage is cleared. Then replace the tile below, and try with the wire to clean the tiles above the basin, so as to tap the water above the obstruction. If this cannot be done, or if the drain ten feet below is clogged, it will be necessary to uncover the tiles in both directions until an opening is found, and to take up and relay the whole. If the wetting of the ground is sufficient to indicate that there is much water in the drain, only five or six tiles should be taken up at a time, cleaned and relaid, -commencing af

the .ower end,-in order that, when the water con mences to flow, it may not disturb the bottom of the ditch for the whole distance.

If the point opened is at a junction with the main, ex. amine both the main and the lateral, to see which is stopped, and proceed with one or the other, as directed above. In doing this work, care should be taken to send as little muddy water as possible into the drain below, and to allow the least possible disturbance of the bottom.

If silt-basins have been placed at those points at which the fall diminishes, the obstruction will usually be found to occur at the outlets of these, from a piling up of the silt in front of them, and to extend only a short distance below and above. It is not necessary to take up the tiles until they : are found to be entirely clean, for, if they are only onehalf or one-third full, they will probably be washed clean by the rush of water, when that which is accumulated above is tapped. The work should be done in settled fair weather, and the ditches should remain open until the effect of the flow has been observed. If the tiles are made thoroughly clean by the time that the accumulated water has run off, say in 24 hours, they may be covered up; if not, it may be necessary to remove them again, and clean them by hand. When the work is undertaken it should be thoroughly done, so that the expense of a new opening need not be again incurred.

It is worse than useless to substitute larger sizes of tiles for those which are taken up. The obstruction, if by silt, is the result of a too sluggish flow, and to enlarge the area of the conduit would only increase the difficulty. If the tiles are too small to carry the full flow which follows a heavy rain, they will be very unlikely to become choked, for the water will then have sufficient force to wash them clean, while if they are much larger than necessary, a de. posit of silt to one half of their height will make a broad,

flat bed for the stream, which will run with much less force, and will be more likely to increase the deposit.

If the drains are obstructed by the roots of willows, ot" other trees, the proprietor must decide whether he will sacrifice the trees or the drains; both he cannot keep, un ». less he chooses to go to the expense of laying in cement. all of the drains which carry constant streams, for a dis : tance of at least 50 feet from the dangerous trees. The trouble from trees is occasionally very great, but its occur : rence is too rare for general consideration, and must be met in each case with such remedies as circumstances sug. gest as the best.

The gratings over the outlets of silt-basins which open at the surface of the ground, are sometimes, during the first year of the drainage, obstructed by a fungoid growth which collects on the cross bars. This should be occasionally rubbed off. Its character is not very well understood, and it is rarely observed in old drains. The decomposition of the grass bands which are used to cover the joints of the larger tiles may encourage its formation. .

If the surface soil have a good proportion of sand, gravel, or organic matter, so as to give it the consistency which is known as “loamy,” it will bear any treatment: which it may chance to receive in cultivation, or as pasturo land; but if it be a decided clay soil, no amount of drain.' ing will enable us to work it, or to turn cattle upon it when it is wet with recent rains. It will much sooner become dry, because of the drainage, and may much sooner be trodden upon without injury; but wet clay cannot be worked or walked over without being more or less puddled, and, thereby, injured for a long time.

No matter how thoroughly heavy clay pasture lands may be under-drained, the cattle should be removed from them when it rains, and kept off until they are compara. tively dry Neglect of this precauţion has probably led

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