E MB

378

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injury; this slope should therefore be formed according to theexposure of it to the winds and tides : a contrary opinion has,however, been held by some engineers, and the formation ofupright walls properly faced has by them been consideredbetter adapted to resist the action of the water. Figure 12,is supposed to be a section of an embankment in which thebase or horizontal line g h should at least be three times theperpendicular height hi-, but Im, the inside slope, need notbe more than three-fourths of the perpendicular height, thatis, nine inches for every foot of rise. The inside slope shouldhe faced with turf likewise, laid with the green side down-wards, as in common sod walls. Some expert sodders canfinish this sort of work extremely neat by setting the sod onedge, according to the slope intended to he given, and withproper mallets and beetles ramming the earth hard behind,which consolidates the work as it advances, and tends torender it durable. As soon as the first or lower course isfinished, the upper edge of the sods is pared with a sharpknife quite even, by laying a rule to them, and then they goon with the second course, which they finish in the samemanner, and thus proceed until the whole height is completed,which, when properly finished, has a smooth and beautifulappearance, not a joint between the turfs being seen. Whereturf is used in covering the outside slope, it should all he laidwith the grass uppermost, as already noticed, and be wellbeaten down with a flat sod-beetle for the purpose, and inorder the better to secure them, it may be proper to drivesmall stakes, about eighteen inches in length, through everysod. In cutting sods for this use, they should be taken up ina careful manner, and be all traced by a line of the samebreadth ; their edges being cut as even as possible, that theymay make the closer joints, which will tend very much totheir security, until they are grown properly together. Inlaying the different courses of such sods, care should also betaken that the joints of the one be covered by the other, inthe manner that good brickwork is made.

Where it is proposed to reclaim a piece of land, uponwhich the sea ebbs and flows every tide, to a greater depththan in the foregoing case, as in a creek, or on the side of alarge river, a different mode of proceeding must be pursued,according to the soil, and the nature of the materials to beemployed. Where plenty of stones can be readily procured,a hank may he formed of them, with a mixture of clay, eitherby means of land-carriage, or, which in some instances isbetter, by conveying them in flat-bottomed boats, or punts,and throwing them over-board until the hank is formed.Where stones cannot be easily had, clay, or other materialsproper for the business, may be thrown in, in sufficientquantity, in the same manner, with perhaps nearly equalsuccess. It is supposed that most of the embankments inHolland were formed in this way, the clay dug from thecanals being made use of for the purpose. In either case itis requisite to fix up strong poles before the work is begun,as guides for laying down the materials. Proper sluicesmust likewise be laid in suitable directions for taking off theback-water when the tide ebbs, under the inspection ofthe engineer. Much, in all cases of this sort, depends on askilful engineer, who is capable of suggesting and contrivingvarious means of facilitating the buisness, and of obviatingthe difficulties that may arise in its execution. A person ofreal genius is often capable, by his different contrivances,of rendering the accomplishment of a great undertaking com-paratively easy, which to others would be almost impracticable,or carried on at such a heavy expense as to counterbalancethe advantages to be drawn from it. In cases of the kindjust noticed, he might suggest the erection of stages or plat-forms, in such a manner as to carry on the work at all times

of the tide, which would be an immense 3avin ° are botfjdelays caused by the tides in this sort of busin® 88 t r ive®tedious and expensive. Waggons might likewise b 0 titi®?in such a way as to carry on such platforms large H ^of materials at once, which could be easily eB1 P j„ giic* 1filled ; and at the same time he drawn by machinery) c9 r'a manner as to save much labour and expense, t>riage and tidework. w ],;ch l3 ’

There is another species of sea embankment, fetf

perhaps, the most important of any ; as ^er® 0 f la 11 ®estuaries, or mouths of rivers, in which large trac ' flt tb®may not be gained by it. The shoals or flats i® - ® r icl> estentrance of such rivers, are mostly composed vltheto-tand most fertilizing particles, brought down fro® gucl 1and circumjacent country through which they ^ ^

shoals and flats may, therefore, under proper m a ®Vj e plain 8 'in most cases readily converted into the most * e . r , t ;ng d * eIn these situations the first object is that of cowhole river into one stream, and preventing its °? e \ iar gea wider extent than is merely sufficient for its “ isc et ‘i, e r,it may be better, perhaps, to alter its course altog j ia g b e ®^cause it to he discharged at some other outlet. r ;yer ,9found by experience, that where the course of in t0

changed in such a manner as to make it discharg® p or e, tbthe sea at a different place to that where it ®® acC u® uformer place will, in a few years, by the contin i'bVStion of sand and mud brought in every tide, be s0 . tge if ( inand raised above its former level, as to form of J . nce , ,course of time, a bank, that, with a very little a ® s » re car rie .exclude the sea; for as the current of the river be ^ wa v3 gaway all that sediment which the motion o ^ it ^naturally stirred up, from its being now re® cs®

obvious that all or most of the muddiness will no ea t P 11ried farther up the old channel of the river, but a t,efof it be deposited there as the tide recedes.

) . n a "I'dtime 3 :

, ° rand

a 3

made at spring-tides can be easily distinguis en „„-rest. This curious fact is well deserving of the ^ ver s,all those who have lands situated at the mouths orable tr f„v

in®?

,flC&

s*& e

T H.UOC „„„ „ avc JUUuo olluuicu _

there may in many such situations be consider*®- .gained at a very light expense. But though this f» cexist in some places, as has been proved by s ,nevertheless it is supposed that the effect cannot be “ { of® all situations. Where there is a great extent ot „ pmuddy shores, the motion of the waves will no doubt ^the mud and sand, and carry great quantities of tlie ®, e t ;dewith the current on the flowing of the tide; and when - e iebbs, though some of the lighter particles will be ^away again, yet it is reasonable to suppose the he* e xc e P lwill be left behind. If the shores are bold and tl‘ lS

no

are j eS 3

just near the entrance of the river, there wn ^ omud ; but on such shores there can, indee ^ gflIoe jf

occasion

narrow

■.auy,, at f °ti, o emb ! nklng ’ un less perhaps in s^-

the sea were excluded^ ^ s P readil) g out ' vide , “jV

‘" ch c, " k " * 8 M

between e the r ri‘ land w Strict of the coun T ° f Norf ^ 0 f tbe

mostWehland l.TT and 0use > immense

uch as is comvosed of the muddy dep

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b»'

ye

most rich land, such as is composed of the „;ltif>U> *"-£

left by the tides and floods, which is there cal® , 0 f W®been obtained by means of embanking. This ’ ^ pihas sometimes been undertaken by the tenants ot ^ t ^ e n iof marsh, in consideration of having the land > r ®® ^ e eo veone years But in these cases the banks have ot

oi it oe aepositea tnere as tne tme -- , .

ound that in spring-tides and particular winds, thisis deposited in larger quantities than at other ti,ne f’ nlft ti ° n ’making a perpendicular cut in the ground under reci ^ gge

the different layers are found to be so distinct, tn« t [,e— O- ---j; ot ; no . u ished A 0 ® „ of