The different kinds of sloped embankments may be formed either with common earthy materials, clay, mud, or a mixture of these several different substances; and any other matters which are capable of uniting into a solid, firm, compact mass, may be had recourse to for the same purpose. Where the sides next the sea or other waters form angles of from 20 to 30, or even 35 degrees with their bases, they may be coated with sand, the shells from the sea, or coarse gravel from the borders of the shores. And stones, broken down to unit; wm sizes of a few pounds in weight, may be employed in a similar manner. Where none of these substances can he procured in sufficient abundance, a method practised in Holland, of covering them with such perishable materials as mats, reeds, straw, hark, and others of the same nature, may be had recourse to ; but these are obviously disadvan tageous, as requiring very frequent renewal. They might likewise be protected by a low fence of brushwood fixed in an erect manner all along at the bottom of the bank, of an equal height, as tending to break off the violence of the waves. Another method might also be employed, which is that of covering the whole front of the bank with brushwood, either made into bundles, or in the manner of wicker-work, or fixed down in a neat manner by means of long poles and strong hooked stakes. And thrther, they may be laid in the form of a causeway, with stones in moss, or covered with wicker-work applied upon the mossy material when spread out over the bank. Many other modes also may be adopted under particular circumstances.
In all cases where the sides and slopes towards the sea constitute angles of front 35 to 45 degrees with their bases, as in Figure 8, recourse may be had to stones of the flag kind, as coverings, which should be jointed with cement mortars formed in some of the ways we have mentioned above. And where these sorts of stones cannot be provided, if clay can be found, proper kinds of bricks may be made, and used in the same way as the stones. Where the slopes or inclined planes are from 40 to 45 degrees, it is frequently more cheap and economical to have them covered with stones of about six or eight pounds in weight, applied to the thickness of a foot and a half, or nearly two feet ; or these may be used on a bed of common moss of three inches, or of peat-moss of the flow kind, of six inches in thickness, spread upon the banks, only to the thickness of six or eight inches. Stones of these kinds may likewise be formed into a sort of causeway, or be laid in strong day, and their surfitces jointed with lime or a strong cement mortar, which has the property of quickly hardening, and of enduring the operation of the air and tides, which alternately act upon it.
There may likewise be cases in which it may be the most advantageous practice to have the sides next the sea or rivers protected by coverings of wood only, in which case, larch may be the most proper, or such others as are durable, haying their surfaces covered over with pitch and some sort of sharp sand. And old sail-cloth, or oil-cloth pitched and coated over with sand in the same manner, or even thin plates or metals, have been suggested as useful in particular instances.
In a paper read before the Institution of Civil Engineers in May, 1841, the [Ion. Mr. Stewart gave a very interesting account of the application of peat to the purpose of building "sea walls." The author described some embankments
constructed with it on the estates of his brother the Earl of Galway, to reclaim various portions of land, to the amount of many hundred acres, and stated that it had been found to answer extremely well, for several reasons, the most prominent of which were, that the blocks of peat, when well rammed down, grew together, thus forming a complete " puddle" wall ; and that from its spongy nature it was not liable to crack in dry weather like clay, when any portion of it was in water, as moisture was in that case drawn up to all parts of it.
It is evident that great quantities of land might in many situations be obtained from the sea and large rivers, by the of proper embankments. Some notion of this may indeed be formed by a careful examination of such lands as lie along their shores and banks, by ascertaining the distances to which the waters ebb out at common tides, as it is found ')y experience, that at least one-half of the extent of land, Inns uncovered in any particular situation, may be gained ; hence, throughout the whole kingdom, it could hardly be estimated at a less quantity than from two to three millions of acres, but it is probably much more than even the last quantity, if it were capable of being ascertained with any degree of accuracy or correctness.
Importance of the extent and the value of the lands which arc capable of being gained by these means are fully considered, there can be no doubt of their being of the greatest consequence to the interests of the country. It has been well remarked by a late writer on this subject, that there are numerous places in the kingdom where vast improvements may be effected by the judicious applica tion of these means. Vast tracts of and of the best kind may not only be gained from the sea, but likewise from the large rivers and lakes, besides the beneficial consequences which must necessarily arise from the prevention of such rivers from overflowing their banks, and injuring the level grounds in their vicinity by such inundations. In some eases, it is supposed, that by raising a bank of only three or four feet in height, at a very small expense, some thousands of acres might be prevented from being overflown, the crops from being carried away, and much other mischief from being produced. In other instances, the forming of very trifling banks might be the means of obtaining much extent of country, which in its present state is of but very little ialue; yet so indifferent are people in general about improve ments of this description, that though immense tracts are year after year overflown, and the most dreadfill devastations committed, they have recourse to no means of prevention ; nay, even though the sea itself, says the writer, as if to rouse them from their inaction, presents to their view twice every twenty-four hours, large tracts that might by proper means be made of very great value, yet these repeated invitations are disregarded, and no attempts are made to possess what might, in many cases, be so easily and so advan tageously acquired. It is certainly extraordinary and unaccountable that the acquiring of distant posses-,ions should he eagerly sought after, and considered of so great importance to us as a nation, when the addition of land in our own country by the reclamation of it from the waters, must be in every point of view so much more valuable.