66 
Trunk Drainage. 
again, joins the great water communication of central England. 
Beside the traffic in coal, com, and timber, and heavy goods, 
which will lade the boats in spite of an opposing contiguous 
railway, it is anticipated that a considerable amount of freight 
and tonnage will arise out of the recent discovery of iron-stone in 
various spots upon the edge of the valley between Northampton 
and Oundle — this being worked and sent to the Staifordshire 
smelting furnaces. 
The works for the drainage of this vallei/ will of course princi- 
pally consist in those above-mentioned for the navigation, the 
two interests having been made identical. There will be the 
improvement and sinking of the river, the remodelling of the old- 
fashioned small-arch bridges, and the variety of alterations to be 
applied to mills, weirs, staunches, &c. 
It is not supposed that the surface of the river will be much 
lowered during the period when the floods are actually descending 
from the uplands ; but they will be held in from overflowing in 
an injurious manner, and will be quickli/ delivered and gone. 
Owing to the necessarily high level of the water, the meadows 
will not be able to drain into the river at its nearest point ; but 
their mains will consist of ^''back-drains," led along under the 
banks of the " mill-pond," " navigation," or whatever the river 
may be denominated according to its use at different parts of its 
course. These drains, connected with proper surface ditches, 
will enter the river through flood-gate sluices situated at points 
loioer doivn the stream than the lands which theij respectiveh/ drain ; 
this being easy of accomplishment, because the valley has a 
natural fall of 2 to 5 feet per mile ; and the mills being numerous 
and closely following each other, the drains will run but a short 
distance to reach the next " level," or step lower in the stream. 
By this arrangement tiie rapid and swelling hill-waters will pass 
by or through the meadows confined in an embanked channel, 
which, though let down in successive steps, still has a very con- 
siderable average inclination, while the slowly-moving drainage 
of the flats accompanies it in lower-lying horizontal side drains, 
until arrived at the same level, when it will be able to enter. It 
is calculated that the improved river will, by this means, insure 
to all the low lands in the valley a clear drainage of from 2 to 4 
feet, or, in other words, leave the surface of the meadows at that 
height above the ordinary level of the water in the main drains. 
This will give sufl&cient depth for subsoil drainage, without which 
the improvement, though valuable, would not be worth all the 
labour and outlay bestowed upon it. Tiie district will also pos- 
sess tlie essential conditions needful for irrigation — a fresli-water 
stream on a permanent level, sufficiently elevated to supply a 
flow over the surface of the meadows, coudjined with a competent 
