Broadlands Drainage. 
345 
the water level ^\it^lill its region rises ; and the water wliicli finds its way on 
all sides into the valleys imijerceptibly from the chalk, by overflowing the 
margins of the impervious alluviuiu lorming the bed of the valley, or by 
oozing throngli the porous peat, is very considerable. It is therefore necessary 
to provide for this extraordinary inllux of water." 
It will be observed that the effect of the system of works here 
recommended would be to increase the sujyphj of water, and to 
originate rather than destroy water power. 
" As the saturated surface of the valley is constantly presented to the action 
of the sun and wind, and the peat soil is peculiarly susceptible of capillary 
action, the amount evaporated will be found to exceed on an average of years 
the proportion quoted from the porous chalk by at least one-half. The differ- 
ence, therefore, whatever it be, between the evaporation from a constantly wet 
surface and that from a drained surface, will represent the loss by evaporation 
to the miller for power, and the irrigator for water ; a loss which, altliough 
perhaps neither the one or the other would imagine it, in the valley of the 
Test amounted to 750 tons per annum from every contributing acre of land. 
" But this is not the whole of the miller's loss hy the present undrained 
condition of the valley. It is manifest that that portion of the rainfall which 
usually filters through a, porous soil, and gradually finds its way out again at 
a lower level, in the present saturated state of the land flows directly over the 
surface to the sea. This loss might be in a great measure saved by rendering the 
surface constantly open and absorbent by drainage, and qualifying it to yield up 
for the use of the mills water which would otherwise never find its way into 
the stream. It may be fairly assumed, that from these two soiu'ces of evaporation 
and overflow, 12 inches of water over the whole surface of the valley are lost in 
every year ; and as 12 inches of water covering an acre of land are equal to 
43,500 cubic feet, or 1200 tons, if this quantity be multiplied by 12,163, 
the number of acres in the valleys, and regard he had to the extraordinary 
amount of fall or inclination of surface peculiar to it, 9J feet per mile — some 
estimate may be formed of the magnitude of the present total loss of motive 
power. To reduce evaporation, and to adapt the soil for the purposes of 
cultivation to the necessary depth, the ruling depth of the main outfall drains 
has been fixed at 5 feet, so that the subordinate drainage may lower the water 
table to a minimum depth of 4 feet." 
Lord Palmerston has employed the General Land Drainage 
and Improvement Company to caiTy out the works of two areas, 
together with a small lateral area, comprising the pleasure- 
grounds and portions of the park at Broadlands. An accom- 
panying plan shows the position of the outfall drains. 
The principal outfall cut A, discharges into the Blackwater 
below the hatches at a, passing under the tributary stream or 
drain at b, and drains the area A. 
The lateral outfall drain B, discharges into the cut A, at c, 
passing under the river Test at d, and drains the area B. 
The outfall cut C, discharges into the tail of Nursling Mill at 
c, passing under the lower end of the principal cut A at f, so 
as to drain deeply and effectively the lands approaching the 
discharge of that cut, forming the area C, which would not 
otherwise- be done. 
It will probably be found that subordinate under-draining will 
