In commencing a work of this kind, however, the first thing to be done is to strike out the intended line of it, setting out the breadth at the base, also the width of the excavation or trench to be made in the inside, from which most of the materials that compose the bank are to be taken : this trench serving also as a drain to keep the grounds within dry. There should also be trunks or sluices at different parts of it, to shut off themselves against any external water, and to open when the tide ebbs, to let out any water from within. 'l'hc width of it should be proportioned to the quantity of materials required from it, for the raising of the embankment, as eight, ten, or fifteen feet wide, and three or flint. feet deep. leaving a berme, or space, between the edge of the trench and the inner bottom of the embankment. If the soil be strong, one foot or eighteen inches will he suffi•ieut for this purpose ; but I if loose or sandy, three or four feet at least will he required. The more easy and gradual the external slope is made, the less sudden the resistance ag,ainst the sea will be, as has been seen above, and of course the embankment be less liable to injury; this slope should therefore be Ibrined according to the exposure of winds and tides: a contrary opinion has, however, been held by some engineers, and the formation of upright walls properly faced has by them been considered better adapted to resist the action of the water. Fqpire is supposed to be a section of an embankment in which the base or horizontal line y h should at least be three times the perpendicular height h i; but I in, the inside slope, need not be more than three•fonrths of the perpendienlar height. that is, nine inches for every Pout of rise. The inside slope should he faced with turf likewise, laid with the green side down wards, as in common sod walls. Some expert •odders can finish this sort of work extremely neat by setting the sod on edge, according to the slope intended to be given, and with proper mallets and beetles ramming the earth hard behind. which •onsolidates the work as it advances, and tends to render it durable. As soon as the first or lower course is finished, the upper edge of the sods is pared with a sharp knife quite even, by laying a rule to then:, and then they go on with the second course, which they finish in the same manner, tuol thus proceed until the whole height is completed, which, when properly finished, has a smooth and beantifid appearance, not a joint between the turfs being seen. Where turf is used in covering the outside slope, it should all be laid with the grass uppermost, as already noticed, and be well beaten down with a flat sod-bectle for the purpose, and in order the better to secure them, it may be proper to drive small stakes, about eighteen inches in length, through every sod. In cutting sods for this use, they should be taken up in a careful manner, and be all traced by a line of the same breadtb ; their edges being cut as even as possible. that they may make the closer joints, which will tend very much to their security, until they are grown properly together. In lay ing the difirent courses of such sods, care should also be taken that the joints of the one be covered by the other, in the manner that good brickwork is made.
Where it is proposed to reclaim at piece of land. upon which the sea ebbs and flows every tide, to a greater dlith wan hi the foregoing ease, as in a creek, or on the side of in large river, a ilitlerent mode of p,oceeding must in pursued, according to the soil, and the nature of the materials to be employ ed. Where plenty of stones eau he readily procured, a hank way be formed of them, with a mixture of (•ay, either by means of land carriage, or, 0 hid] in some instances is better, by lug them in fiat-bottomed boats, or punts, and thi owing them oecr-board until the bank is ft trmed.
e stones cannot be easily had, clay, or other materials proper tl• the business, may be thrown in, in sufficient quantity, hi the same in inner, with perhaps nearly equal success. It is supposed that most of the embankments in Holland were turned in this way, the clay dug from the canals being made use of for the purpose. In either case it is requisite to lix up strong poles lietiire the work is begun, as guides for laying down the materials. Proper sluices
must likewise be laid in suitable direction for taking off the back-water when the tide ebbs, under the inspection of the engineer. Aluch, in all cases of this sort, depends on a skilful engineer, who is capable of suggesting and contriving various means of fiteilitating the business, and of obviating the difficulties that way anise in its execution. A person of real genius is often capable, by his dit11•rent contrivances, of rendering the ticcomplishinent of a great undertaking cow pau•ativclr easy,which tooth its would be almost impracti or cat rigid on ;It such a heavy expense as to counterbalance the aileantages to be drawn from it. In cases of the kind just noticed, he might suggest the erection of stages plat forms, in such a manner as to carry on the work at all times of the title, which world be an immense saving, as the delays caused by the titles in this sort of business are butll tedious and expensive. Wavons might likewise be contrived in siteh a way as to carry on such platforms large quantities of materials at once, which could be easily emptied and filled ; and at the same time be drawn by machinery, in such a manner as to save much labour and expense, both in car riage and tidework.
There is another species of sort embankment, which is, perhaps, the most important of any ; as there are few estuaries, or months of rivers, in which large tracts of land may not he gained by it. The or flats formed at the entrance of such rivet's, are mostly composed or the rh.he,t and ow-4, fertilizing potieks, brought. down from the towns and cir•umjacent country through which they pass. Such slam's and flats may, therefore, under proper be in most crises readily converted into the most fertile plains. In these situations the first object is that of collecting the it hole river into one stream, and preventing its overspreadrn!,i wider extent than is merely sufficient ib• its discha•ge: or it may be better, peihaps, to alter its course altogether, and eause it to be discharged at some other outlet. It has been found lay experience. that where the course of a river is changed in such a manner as to make it dischar7e itself into the sea at a different place to that where it did betbre, the lbrmer place will in a few years. by the eiontinned neeutnit'a thin of sand and mud brought in at every tile, best, choked np, and raised above its ft:tailor level, as to ni itself. in the course of time, a bank, that with a very little assistance, will exclude the sea ; for as the current of the river heft ire carried away all that sediment which the motion of the waves naturally stirred up, from its being now removed, it is obvious that all or most will not be ear ried up the old channel of the river, but a great part if it he deposited there as the tide re•cedes. It has been found that in spring-tides and particular winds, this sediment is deposited in larger quantities than at other times, and on a perpendicular ent in the ground under reclamation, the dillorent lay ers are found to be so inri, that flake made at spriistides can be easily distinguished front the rest. This curious filet is well of the attention of all those who have lands situated at the month of as there may in many such situations be considerable tracts gained at a very light expense. But though this fact may exist in sonic place's, as has been proved by experience, nevertheless it is supposed that the effect cannot be the in all situations. \\There there is a great extent of flat or uundciv shores, the motion of the waves will no doubt stir tip the 11111(1 and sand, and carry great quantities of them along with the current on the flowing of the tide; and when the tide ebbs, though some of the lighter partic'le's will he carried awav again, yet it is reasonable to suppose the heavier ones will be left behind. lithe shores art: bold and rocky except just near the entrance of the river, there will be less of this but tut such shores there indeed, be little or no occasion fur embanking, unless perhaps in some creeks, narrow at the entrance and spreading out wile above. If the sea were excluded from such creeks, a great deal of land might probably he gained.