§10 AGRICULTURAL REPORT. 
in its structure than that of a place where the climate is colder and the growth ot 
vegetation is slower and Jess luxuriant. 
{t has been remarked that spongy, vegetable soils will retain water, when sandy 
and petreous soils will not, and the work of drainage will be increased in proportion 
to the quantity of vegetable matter found in the soil. It also occurs that this rapidly- 
formed soil is less fitted for the construction of water-tight embankments than that of 
a more gradual deposit, on account of its being more permeable to water, and it is often 
found necessary, therefore, to reject the soil we propose to reclaim, as a material for the 
embankment, and use that from another place. 
While locality and climate materially affect the manner of reclamation, prevailing 
winds also exercise an influence by their action on the tidal wave. In exposed situa- 
tions, the winds exercise this influence to such a degree as to necessitate a complete 
change in the plan of reclamation, especially on the tidal marshes along the coast and 
the shores of our rivers. According to the course of the river, against the overflow of 
which embankments are erected, as well as the direction of the opening by which the 
waters reach the sea, the wind, at certain seasons, causes a raising of the tide wave 
above its ordinary level, and of course necessitates higher and stronger embankments 
to resist it. 
Reference is net made to the semi-monthly occurrence of spring tides, but to the pow- 
erful effect of strong winds on the surface of water, forcing it in the direction in which 
it blows. When a strong wind and a spring tide occur at the same time, the tide will 
be raised over the level of spring tide in proportion to the strength of the wind; and 
when both meet a heavy freshet after a rain storm, the increased volume of the stream ° 
is not unlikely to overflow the banks, and inundate the surrounding country for many 
- miles, doing much damage to property, and sometimes cansing loss of life. 
In level countries the wind blows in a downward direction at an angle of something 
over 18° with the horizon. The pressure of the wind is in proportion to its velocity— 
the former increases as the square of the latter. 
The following table of velocities and pressures.of the wind is taken from Burnell’s 
Hydraulic Engineering: 
5 S 
a |g 
* Name of wind. $5 eS 
o> @ ore 
as Be 
an a) 
Ft. In.| Pounds. 
Light breeze, hardly perceptible -..---..----- e--0 sceece= Oe eke 1 8 0. 04989 
Gentle DreeZ0. ~~ oon. ton - He e—n nw na ae pe eee ewww enna nee es 3.4 0. 19756 
rs ce tone n= bp ae see eas eee gee st eees Mecere stn ree 6 8 0.79130 
Rather strong wind, best for sailing -.......----. 2-5 .-.-2---. 18 0 6. 06996 
PUNT ee eine Cries Seino as ness se eae tee C ania sees Oat 33 0} 20.06690 
Wine cing AVAT oo oe we ete eo re ctenae of oes eete ae ones eae ee 66 0 | 80.26760 
WenINGRMOVISIOTIO. Goo aoe ee fae ce lee eee eee cleb waceee sees 70 0 | 101. 62790 
Gren BiOMm me ot seer tees ee me oa 2) ein ely Ana Dee ee 90 0 | 146.34430 
Elgrrican vas tN Tie seo sae Gta ie ne See aoe cee ee 8 118 0 | 260. 05670 
Hurricane able to tear up trees, &c., &e ..----- 2s oreo ee ene ee 150 0 | 406. 51180 
An instance of the effect of strong wind on water is mentioned by Franklin. A pond, 
nine miles wide, and of an average depth of three feet, was acted on by a strong wind, 
which forced the water from one side so that it was laid bare, and the depth of water 
on the other side was increased to six feet. 
Next to the influence of winds and waves on reclamation works, is the action of 
currents: Where the shore is concave, if would be imprudent to erect embankments 
close to the water-line, unless some protection in the shape of masonry or piling be 
placed against the wearing action of the current; while, on the other hand, when the 
shore is convex, the embankment may be placed even at the water’s edge, as the fore- 
shore will continue to gain in the latter case as it loses in the former. 
In like manner, on sea-ceast embankments, where the bank is likely to be washed by 
any of the numerous currents created by the movement of the tides, the greatest cau- 
tion should be exercised in protecting the works from injury, and the exterior slopes 
should be strengthened in the best manner to resist the action of the water. 
To preserve the embankment against the damaging effects of frost, it is well to cover 
the face of the exterior and interior slopes with thick sods, cut from the surface of the 
marsh at the time of the construction of the bank, by which means a protection is 
afforded to the bank by the covering of grass, and the frost is not permitted to pene- 
trate 50 deep into the soil composing it. 
