part of the bank GIK, and facing up the line IKL with ftones or turf, fo as to make it become a fence to one fide of the field that it preserves from inundations.

But, if the furface of the ground is extremely low, fo as to be but little above the level of the water, as at LM, (Fig. 15th and 16th,) then, inftead of raifing the banks on each fide to the height of AB, (Fig. 16th,) it will be more adviseable to raise them only to the height of the line EF; as in that cafe it would be very difficult to find fo much earth as would form the banks at AKD and CGB, although there will be no difficulty in forming the smaller ones KEL, and GFM: And, as the area EFGCDK, is equal to the area ABCK, thefe lower banks will contain an equal quantity of water within them, as the higher ones would have done ; the greater width between them making up for their want of height.

In

In this way, it will be in the power of any man fo to proportion his banks to the circumstances in which he finds himself placed, as in the eafieft manner to accomplish his defign; for, if he has plenty of materials at hand, he may rear his banks to a greater height, and confine the river to a narrower course; and, if he finds a deficiency in that respect, he may make them of a smaller height, and allow the river to fpread to a greater breadth.

§ XXX.

Method of fecuring the Fields thus defended from the River, from the Danger of being overflowed by extraneous Water coming from the high Ground behind them.

It is neceffary to defend these haughs, not only from the inundations of the river,

but

but also to preserve them from being overflowed by any other water that might come down upon them from higher ground. On this account, it will be neceffary to allow any rivulets that may flow through these, to fall into the river without any obftruction; banks of the fame kind being continued along each fide of these as far as the haugh-ground extends. And, if the back part of these haughs, where it borders with the higher ground, be bounded with a good ditch to intercept the water that may fall from it, with openings at proper places into the river, they will be effectually fecured from all extraneous water whatever, and remain quite dry, while the water all around them is higher than the furface of the ground in them, if the poffeffor shall so incline.

To illuftrate this more diftinctly, I have fubjoined the plan of a small part of a river, with haughs on each fide of it, fecured in this manner (at Fig. 17th), in which AB represents

prefents the river fecured by its bank on each fide; C and D, rivulets that fall into it, confined by banks on each fide of them, as far as is neceffary; EFG is the ditch that separates the low from the high ground; which receiving the water that defcends from the heights carries it in the direction EF, till it falls into the rivulet upon the one fide; and, on the other fide falling towards G, it flows on till it comes to fome other part, where it may be found neceffary to make an opening for it into the river. The lines H, I, K, are the dikes dividing the haugh into fields of a moderate extent, which may be nearer or farther from one another as the field has more or lefs declivity. These dikes fhould be of a confiderable thicknefs, and may be formed of the earth taken from a ditch on each fide thereof, (as at Fig. 19th,) which ditch should be carried quite round each of the fields, in order to receive and

carry off

any water that may fall upon them, or any moisture that may ooze out of fprings.

§ XXXI.

Of freeing the Fields, thus fenced, from Water that might arise from Springs within the fame.

But, it is not only neceffary thus to secure our fields from being hurt by water from the river or higher ground, but also, to provide an outlet for the water that may be within them. For, unlefs fuch outlet be provided to carry off the fuperfluous water that may fall upon thefe fields from the clouds, or rife from fprings within them, our improvement would be very imperfect. On this account, it will be neceffary to be attentive, when forming the bank, to leave a fmall