16 
MIDDLE LIAS OF NORTHAMPTONSHIRE. 
Jan., 1889. 
with the Nen below Peterborough. For twelve miles below 
Peterborough a large basin or reservoir has been constructed, 
by making banks on each side of the river at an average 
distance of half a mile apart. This “wash” as it is called, 
has a superficial area of about 3,750 acres, or 1 per cent, of 
the area draining into it, and is sufficient to hold 1 inch 
depth of rainfall over the drainage area above it. An 
extraordinary flood fills this to a depth of 7 feet or more, but 
the water has never run over. The wash affords good 
pasturage in summer time. Like several of the other 
remedies referred to, this is only a partial one, however, for 
the heaping up of water in this wash both increases the 
velocity of discharge between it and the sea, and increases 
the height of the flood in higher parts of the valley. If this 
system of making flood-banks were carried out along the 
whole valley subject to floods, with a gradually decreasing 
sectional area, and the tributary streams were similarly 
treated to above the flood line, floods would be almost 
unknown outside this area, and only the superficial 
accumulation of water in a soil at present admitting of no 
effectual drainage would remain to be dealt with. 
With regard to the other remedies, it is easy to see that 
if the flood-gates and overshots were made progressively larger 
towards the outfall, the latter being constructed so as to have 
a sectional area of discharge below the flood line equal to 
that of the total sectional area of the river above them, and 
also to give a less vertical fall to the water running over 
them, by continuing the inclined surface to about the low- 
water level of the river ; if the river were progressively 
cleaned out in an opposite direction, and the locks and other 
artificial obstructions intelligently regulated, the narrow 
parts made wider, and the winding parts straightened, a very 
great improvement would be brought about; to the extent of 
preventing many floods, and facilitating the discharge of all. 
Such improvements carried out in the upper part of the 
stream only would, of course, add to the injury lower down, 
by bringing the water to these latter more quickly. The 
legal and pecuniary difficulties connected with the carrying 
out of these details would be very great, and the former, per¬ 
haps. under the present condition of legislation, insuperable. 
It will have been noticed that the general tendency of 
nearly all the plans so far considered is to get rid of the 
water more rapidly than the present condition of things 
permits, so that a great scarcity of water would prevail 
during an ordinary summer. They all have the drawback 
that the water got rid of would do no useful work. 
(To be continued.) 
