P to low-water mark. Upon this a bed of rushes, fastened

°Wn by stakes and wattles, is laid ; and the tipper por-

of the bank is faced with fascines of a regular slope°‘ 1 to 1.”

Embankments against rivers may be divided into two'ods; namely, such as are for preventing their encroachingn _the adjacent lands, and for protecting those lands and the®'ghbouring level country from being overflown, whene Water rises above its ordinary level. It may be remarked,a t where the course of a river is a straight line, or nearly°> it hardly ever makes any encroachment upon its banks,tl? ' SS , P er i' a P s ) i n very large rivers, when they rise aboveei r common level, either owing to an increase in the waters,f their being, in some degree, affected by the tides. Intb • case > the waves occasioned by a strong wind, wheree r >ver is wide, will moulder away the banks on that sidePon which it blows, unless prevented in proper time. Thisa y be done either by securing the bank properly withones, or by driving a row of long piles pretty close together> a Httle distance from the shore, the piles being of such at> n oth, and so driven, that their tops may be always abovec highest rise of the water.

P'les dri

x t/ ~

. —_ _ It is surprising the effect that

f tven in this manner have in resisting the power of the"T 8 in such situations.

en .° me years ago, when Mr. Beatson was on duty as an^eer at a fort near Portsmouth, built on a point of landthe 1 ex Posed to the sea, the waves made such havoc, thathyii^.^l® °n that side were constantly giving way, althoughof l 10 ^ ie niost substantial manner; and having bulwarksh 0 ar 8 e heavy stone besides, to protect the foundation:h no e ^ er > a H would not do; those bulwarks were soonlen»ti • t0 P' eces > an <l several times the wall itself. At4 q g 1 11 was proposed to drive a number of piles at aboutlg j° r 50 yards from the fort. These piles were 12 orea ch ° les * n diameter, and driven about one diameter fromthe 0t ' ler ne arly in a straight line, parallel to the wall whereg r ' Vaves did so much damage. They were driven into the9 f nc * with a pile-engine till perfectly firm, perhaps 8 orth e ^ ee P> and about 2 feet of the top of them left abovere Cg . eve ^ °f high-water mark. After this was done, the wallth e f Ve< ^ no further injury, the space between the piles andthe ° rt f >e tng always perfectly smooth, however tempestuousmight be without. The same simple methodla r 8 5 . lt ’ s supposed, sometimes protect the banks ofitiipl r i Ver s> if exposed to the waves, when other methods

fail.

CncfQ 1 V'suggested, that the most common cause of riversell| ng on their banks, is the resistance occasioned by ahend. In flat countries, apt sometimes to be over-iw, ’ "’here tliere are any such bends or windings in the

straighten the

tiv

rgjtg . - - J --- V* »<

CQ Urse ]t Wou i ( f i )e °f great advantage to u n tvigj uivd U1D0 bst ri as rnu ch as possible ; for, as every impediment orit lc J n will naturally cause the water to rise higher than< lOn s „ er " r * ae would do, and as such bends have that effect,a » r " Uen fiy> in the time of a flood the waters will overflowthe j.: er extent of country, and to a greater depth, than ifif ti, e v ® r had a free and uninterrupted course straight forward.>rie nt ' Vlr| dings of the river cannot be altered, and encroach-making on some part of the banks, it must first beat >otK ei ' e< i' whether the force of the water can be driven to." ■ er ’ ‘ If, for example,

.Llic 1U1UC Ui Ulc

a >'ive r • ace where no injury can be done,

°f sto 18 enc i'oaching on its banks at x, *lyure io, a jetty‘W 0w \ a 1'ttle way up the river, in the direction y z, wouldat| y fa rt ? t ^ ie cu rrent towards w, and might totally preventj*i>ir e , j , er encroachment. On the river Nith, in Dumfries -v l\{ r J, s | stat ed, that a good deal has been done in this waylillar, of Dalswinton, a gentleman of the most enter-

5s

prising genius and most liberal mind, who has paid moreattention, and laid out more money, in making important anduseful experiments, than almost any other private individual.The course of the river, where Mr. Millar lias been carryingon his operations, is said to be nearly as shown at Figure 14b y rslu; at t, it was encroaching most rapidly, and seemedinclined to take a new course towards v, which would havedestroyed some very fine land, and done a great deal of mis-chief in that part of the country. To prevent this, Mr. Millarmade a large cut, about 400 yards in length, from w to r, andthrew in a great quantity of stones quite across the river ats,to direct its course in a straight line from r to w. This had,in a great measure, the desired effect, by totally preventing itsprogress at t, but now it began to encroach on its banks at u.He at first endeavoured to prevent this by driving in, at aconsiderable expense, a number of piles at a little distancefrom the bank, and wattled them with willow branches, &c.,thinking thereby to protect the bank. The piles were drivenin with heavy mallets, apparently firm into the ground ; theycontinued so for some months, till a heavy fall of rain cameon, which swelled the river, undermined the piles, and car-ried them all away. But, indeed, it is in vain to think of pilesdoing any good in such a situation, unless firmly driven in bya pile-engine ; for it is not possible to drive them in properlywith mallets ; this must have been the cause of their givingway so soon. The piles not succeeding, Mr. Millar wasresolved to try another plan ; several of his adjacent fieldsbeing covered with an immense quantity of stories, he orderedthem to be gathered and thrown into the river, so as to forma jetty at x, a little way above the injured bank. Beingobliged to go from home about that time, and to leave theexecution of the work to some country-people, they carriedout this jetty too much at right angles to the stream. It hadnot, therefore, the desired effect, but rather made the matterworse than before ; for, if a jetty is carried out at rightangles, as at a, in Figure 4, the current will be forced froma to the opposite side of the river at b, and from thence itwill rebound towards c, more violently that it did before.But if a jetty be placed obliquely, as at d, it will force thecurrent gradually towards e, in which position one jetty maydo more good than several placed improperly at right angles.Mr. Millar was, therefore, under the necessity of makingother jetties in this way, and at length had the satisfaction tofind that they answered the purpose intended. Those he madelaterally formed a sort of convex slope, the convexity beingparallel to the current. Strong planks were also firmly set onedge among the stones, their ends pointing towards the river,so that if ever any current came so rapidly as to -move any ofthe stones, it must move them all in a body the whole lengthof the plank. Perhaps this precaution was unnecessary ; foralthough stones are thrown into a river loose in this manner,the slush, sand, &c., that come down the river will soon fillup all the cavities, and render it as firm and solid as a regular-built wall. Mr. Beatson has been the more particular in thisdescription, he says, in order to show the errors that Mr.Millar at first fell into, and the great expense they occasioned,whereas, had he been on the spot himself, and got the workexecuted as he intended, it would have saved a great deal ofunnecessary labour as well as money.

It is stated by the same writer, that the next sort of em-bankments against rivers, are those to prevent them overflow-ing their batiks, and inundating large tracts of country. Thismay be considered as the simplest and easiest of all sorts ofembanking, if judiciously executed. It is, therefore, the moreinexcusable to see, in some places, extensive tracts of therichest meadows completely overflown by every flood, for wantof them.