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Two ordinary-sized rivers rise no more, even in the greatestflood, than five or six feet above their common level, unlesswhen they meet with some considerable interruption or con-finement in their course. But if interrupted or confined, theywill rise twenty feet or more, as is the case with some partsof the river Mersey, already mentioned. If, for example,a given quantity of water is six feet deep, when runningover a space twenty feet wide, it is clear, if that space wereonly made ten feet wide, the water would rise to twelve feet,and if it were made forty feet wide, the same quantity ofwater would only rise to the height of three feet. It is, there-fore, of great consequence, in preventing inundations, to givethe river as much width as possible, by widening everynarrow place. All kinds of obstructions should also beremoved, whether occasioned by windings, shoals, stones,trees, bushes, or anything else. In some cases this may evenpreclude the necessity of embanking ; but where embankingis necessary, let the banks by all means be at a sufficient dis-tance from each other, to contain with ease, between them,the largest contents of the river in great floods. The distanceand height of the banks may easily be ascertained by mea-suring a section of the river when at its highest, orwhen the flood - mark is visible. By not attending tothis, a great deal of money has been thrown away on theembankments on the river Mersey, and after all they donot effectually answer the intended purpose ; a great partof the country being still overflown every time the river risesto any considerable height.

Where a sufficient distance is allowed between the embank-ments, their height need not exceed from four to six feet.If irremoveable obstacles are in the way, which cause theriver to rise higher, the banks must be higher in proportion.In either case, however, the slope of these kinds of banks oneach side may be equal to its perpendicular height, and thebreadth on the top about one-third of that height, which, sup-posing the bank six feet high, the base would be fourteen feet,and the breadth of the top two feet, as stiown at Figure 16,in the Plate.

The materials for making these banks should be taken asmuch as possible from the sides of the river, which will havethe double effect of widening the river and forming the em-bankments ; and there should be a trench on the inside (fromwhich materials may also be got) with some sluices, as for-merly directed, to drain off any water from within ; alsosluices to let in water from the river, if required, whichwould very much fertilize the meadows, if properly laid outfor that purpose.

Such farms as are situated on the borders of rivers are fre-quently, it was observed by a late writer, liable to muchinjury and inconvenience from them : 1st. From part of thesoil being carried away in times of flood. 2nd. From theiroverflowing their banks. 3rd. From their flowing back intimes of flood into the channels of the rivulets and streamsthat conduct the water from the more elevated and distantgrounds to the rivers, whereby these rivulets and streams aremade also to overflow their banks.

In respect to the first, the danger of the soil being carriedaway in time of floods, it is increased or decreased accordingto circumstances, as the form of the banks, the nature of thesoil, the rapidity of the river, and the quantity of water thatlodges on the margins of the banks, or falls over them intothe river. Where the banks of a river are perpendicular,especially if the soil be of a rich mouldering nature, thedanger of part of them being carried away by floods is muchgreater than where they slope gently from the surface ofthe field to the bed of the river, as has been already fullyseen.

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Where that is not the case naturally, they oU S . ce ofmoulded into that form by art; as when a river,being confined in its progress, has a power of efflux a coB) pare^the damage to be apprehended is inconsiderable,with what is likely to happen when, being restrain ^ eB sio°too narrow limits, it is constantly struggling for an u nd® r

of space. Where the soil is rich free mould, and of

stratum, opposite to the greatest force of the water, c0 a-gravel, this struggle never fails to be attended wit i ‘ 0 p c l»ysequences. If the soil and subsoil be one entire mas»^ pres 3or strong loam, and the current of the river does . p r oV«'more upon one part than another, a most substantia ^gcli"ment may be effected by sloping the bank, so that ^ tb evity may be one foot in three or four from the sU1 ^ eC t to, 83

field to the bed of the river. This some may 1

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sacrificing a certain portion of valuable land ; ^idfort^rather, it is thought, be considered as a premium P g ra yekinsurance of the remainder, than as a total loss. n “ or ed.mixed with small stones, can be conveniently jgptbspreading these materials on the sloping bank to o p tb®of eight or ten inches, and till beyond the fl°' vir . andriver, will prove a good security against farther da c5 pe'if the bank be planted thick with any sort of wl , c0I necially the Dutch willow, it will in a short timeimpenetrable fence, while the annual cuttings m a pp 3 'soon be equal to the heritable value of the landrently sacrificed. Where no gravel can be pr° cUie sfl -ai'd e ^sloped bank should be immediately covered with w e ^ bn c ' iturf, pressed down as hard as possible, either w lf }^ ne jnof a spade, or with wooden mallets.

If this be dewing

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beginning of summer, and willows planted ^ p&-autumn, the improvement will be both effectual a v j 0 [eH c3nent. In case the river run with extraordinary^ ne ce 3 'against any one particular part of the bank, it ^ of ^sary to make a fence or bulwark of stone in the r ^ ^ildifoplace ; the best way of doing which, is, in place ^ flS th e ;a wall, to drop the stones in a careless manner, j refl( jy sagmay lie close together on the sloped bank, as agested. . a jf t j,e h* {

This is a much more secure mode of fencing, ^, a jl 4' 1be made with sufficient declivity, than any ® t0I ? g fpe 0°*ever was built for the purpose, and while it * g j,oulIsecure, it is also the least expensive; but car t j,e rb e ’taken to lay the stones all the way from the be c o0 tO °i jtill considerably beyond where the river flows un“ e .

Where the soil is of a strong adhesive nature, an nine

stratum is sand or a pebbly gravel, it becomes w 8 ^

greater degree necessary to slope the banks. ^ - nwhen rushing violently along, has a power * U lf; n ir tO Sl, f^° a Smining the bank ; so that the soil, having notl ° n tit0 3it, naturally gives way, and frequently in _ sucl g ^ n( j tefl ar]to occasion very serious loss both to proprietors ^ 0° .In all such cases, the slope should be ma e ^ t j ]6 s»gradual than where the soil and subsoil are ba 11 g

quality, and such as will nourish aquatic plants.^ req uil !>having been sloped according as circumsta ff jj e re s , 0 fthick coat of gravel, mixed with small ston ^ m a ki*jcan be procured, should be laid on, so as to . nl ay ■' gVnatural beach, over which the river, when in jifficupower to extend itself at pleasure. Should i f 0 r mimpossible to procure such materials as are p ^ gliouling this best of all defences, strong thick s .° cte d : * 1 t oplaced on the surface, in the manner before j j )aVe tit 8if laid on in spring, or early in summer, wi a uta ^unite, and to become one compact body belo ^ is { ,floods (which are those whence the greates uiif aVexpected,) begin to flow. If the subsoil be of a n