to the Firft Volume. 595

few fuch cafes. It has been obferved, that“a carriage might almoft aswell be floating on a billow at fea, as toffi ng up and down on an inclined plane every ten or fifteen yards! When a road is conftru&ted on the principle of the plane, there fhould be no floping of the fides; otherwife the water is impelled by two forces at right angles with each other, and confequently tends ina diagonal line,

To be read at the End of Seétion V. Embankments.—In many fituations ex- tenfive tracts of land may be gained by the jndicious conftruction of em- bankments. In improvements of this fort, the proper forming of the danks contti-

tutes the principal difficulty and expenfe of the undertakings. The particular cir- cumftances of the cafe muft chiefly dire the operator in regard to the fituation, fize, and manner of conftruction, as well asthe nature of the materials which are to be employed. In general, however, the fituation of fach banks fhould be fuch as that their bafes or foundations may not be unnecefiarily expofed to the dire& aGion of waves or currents. Where the quantity of water is in fome meafure limited, as in the cafe of land floods in particular inftances, the greater the fpace it has left to ex- tend itfelf in, the lefs height and ftrength will be requifite in the bank, and the force of the current be leffened in the fame proportion. But where the courfes are liable: to be filled up by depofitions, it fhould be recolleGed that the more the water is confined the f{tronger the current will. be, and the lef the danger of their filling up.

In regard to the line of an embankment it fhould always be even, and as free from irregularities as poffible, in. order to: occafion the leaft poflible reffance to the: currents of whatever kinds..

In forming the bank, the height and ftrength fhould conftantly be made in pro- portion to the depth and weight of water that it may have-to refitt, always having the inner face made to incline towards it, for the purpofe of fupport in the way of a buttrefs.‘The out-face muft be formed in a Moping direction, fo as to approach a. degree of flatnefs, in order to: obviate ref/tznce, and lefien the preffure or weight of the water. On this being properly executed its firmnefs and durability greatly de= pend. In difficult cafes, it is advifed that the outer furface thould: form an angle to a perpendicular line of from forty-five to fixty degrees, according to the force to be oppofed and the nature of the materials employed*.

In refpect to the materials, where the foundation is: good, firm, and folid; and the bank can be contiructed at a fuitable time,. without much interruption from the water, the natural earth of the ground may anfwer perfectly for the body. of the

* Marfhajl.on the Landed Property. of England,