606 AGRICULTURAL REPORT. 
the marsh land reclaimed. Second, the collection and expulsion, by means of drains, 
ditches, sluices, and pumps, of all waters lodged on the marsh or having their sources 
inside its limits. Third, the control of all waters that may afterward accumulate on 
the marsh from springs, rains, or other causes, so that the danger of drowning the land 
may be avoided and the cultivation of the soil be uninterrupted. Each of these con- 
ditions must exist to insure the harmonious working of the other two; the absence of 
one is fatal to the usefulness of the others. In case of the first condition, when we 
undertake to exclude waters having their sources outside the limits of the marsh to 
be reclaimed, it is necessary to erect a dike; but the shape, size, and mode of con- 
struction will be governed by the locality, material, and the amount of resistance the 
dike must offer to the return of the excluded water. The collection and expulsion of 
waters accumulated on the marsh from rains, or the interception of that it its 
source from springs within the marsh limits, will depend considerably on area, loca- 
tion, and outfall, as well as on the power and capacity of pumps and other water-engines. 
The control of the water in the soil and its removal for agricultural purposes will 
depend on the excellence and completeness of the other works, but will also be affected 
by climate and the character and treatment of the crops raised. The location of the 
marsh with respect to high lands is of the utmost importance, as, when adjoining 
upland, it receives the rain-fall of the hills in addition to its own, and unless precau- 
tions are taken to control this irregular addition to its own waters, so that the land 
shall not suffer from it, the third condition for a complete reclamation cannot be said 
to be complied with. ; 
Embankments are necessary for the exclusion of water from an area where the 
source of that water is above the level of the surface to be kept dry. For instance, 
the embankment of a reservoir must of necessity be above the level of the river, spring, 
or other reservoir from which the first receives its supply, unless, indeed, the discharge 
from the latter be equal to that which it uniformly receives, and its embankments lose 
their retaining character, and become simple diverters of the stream. In like manner, 
any space inclosed by an embankment for the purpose of excluding water must have 
that embankment higher than the highest level of the encroaching water, if an inland 
stream, or the highest known range of the tide, if on a tidal river bank or the sea- 
coast, unless, in the case of the inland stream, the water becomes simply guided in its 
course, and not confined. 
As our principal marshes requiring embankments are located along the shores of 
the large bays and inlets, or on the banks of tidal streams, remarks will be confined 
to such marshes and their requirements. In erecting a dike to resist the pressure of 
the tide, the shape, the size, and the mode of construction of the dike must vary with 
the location and the range of the tide. Location aftects it because the bank may at 
one point be sheltered from the eroding actien of the waves, while at another point it 
may be exposed to their full force. It is therefore evident that some dissimilarity 
must exist between the work to be done by the two sections of the bank, and a conse- 
quent difference becomes necessary in their shape, strength, and mode of construction. 
Many plans have been projected for the erection of dikes, sea-walls, and embank- 
ments, each possessing some peculiar merit, while failing to fulfill equally important 
requirements. No particular form of dike can be recommended for all cases, as the 
necessity of each case demands special treatment. The Dutch engineers favor long 
slopes for sea-banks, constructed of sand or other light material, but the length of the 
exterior slope can be safely diminished where a durable material, like stone, can be pro- 
cured, with the additional security of piles and other protection; it is also certain 
that where the material is not adhesive and durable, long slopes, especially facing the 
waves, are advantageous, when not exposed to the face of the ocean waves, as on the 
coast of Holland. 
A base of about five to one, divided between the internal and external slopes, in ad- 
dition to the width of the bank on top, would afford ample base for an embankment. 
Thus, if we require an embankment six feet high to resist the encroachment of the 
tide, we cannot with absolute safety construct it with a base of less than thirty-five 
feet to resist effectually the wash of the waves. This width of base would admit of, 
in the first place, a width on the top of the embankment of five feet and external slope 
of three and a half to one, and an internal slope of one and a half to one. The bank 
with a thirty-five foot base is suited to exposed situations, where wind and wave act 
directly but moderately. Where the bank is subject to a heavy blow from the waves, 
the slope will be so graduated as to receive and gradually deaden the effort of the 
wave as it traverses its surface. 
The shape of the bank is of as much importance as its constraction and dimensions, 
because, if by unsuitable proportions we subject the very best material and workman- 
ship to extreme and unnecessary strains, it cannot be expected that the work of resist- 
ance will be performed as effectually as if due consideration were given to the relations 
which should always exist between the shape, material, and amount of resistance the 
bank is expected to offer to the water. Durable material is not always to be had where 
wanted for embankments, but in the case of salt marshes, with very few exceptions, 
the soil excavated forms a superior material for their construction, ‘Ibis is more gen- 
