36 
Trunk Drainage. 
regulated bj a sluice ; and in the present improvement of our 
own river Nene, it has been found necessary to restrict the right 
of different fens to take in water, as they liave had the power of 
abstracting the whole volume of the river in dry seasons. To 
prevent this, a pipe or tunnel of certain size, or an arrangement 
of locks with double-pointing doors (where a navigable drain 
joins the more elevated river), has been applied, so that one alone 
of all the tracts claiming fresh water in drouglits may no longer 
be able to deprive the others of their share. But these points, 
with others, such as the providing of a requisite number of feet 
depth for navigation, or the relinquishing of water-carriage alto- 
gether ; the removal of water-mills, or the increase of their power ; 
the diversion of the drain-water to be independent of the natural 
stream ; the partial improvement of a river for simple agricul- 
tural drainage, when the flooded lands bear too small a propor- 
tion to the river and its accessory water-interests to command its 
complete remodelling ; and the engineering puzzles often presented 
by marshy or shingly estuaries, tortuous channels, tSlc. «kc., will 
all be set forth in a more practical light in the examples I shall 
adduce. 
8. Actual state of some river or rivers to he described. 
9. Remedy ajiplied to some river or brook to be described. 
The vast works of drainage executed in our fen levels form 
"both our example and encouragement in dealing with the inland 
valleys, beside being the preliminary necessity to the latter class 
of undertakings in the case of most of our larger rivers. And 
though the difficulties may differ in the two cases, they are so 
similar as to be assailable by the same order of efforts. In the 
Fens an expanded country contributes immense importance and 
great power to the work of improving a river ; in the more inland 
valleys a narrow district, attenuated along the length of a capa- 
cious stream, seems at every point less able to cope with its 
swelling antagonist. But then, in the former case, the task of 
giving to a horizontal river a scarcely obtainable fall, and of 
delivering a vast bulk of rapid hill waters in addition to the slug- 
gish drain-water of the flats, through an excavated estuary, and 
against a fenced-out tide of thick water, transcendently surpasses 
the work of merely easing a stream from strangulating impedi- 
ments. Let us, then, by way of introducing our narration of 
river improvements, note down one or two items of outlay ex- 
pended by the fcn-7}ien of the Great Level in trunk drainage. The 
Bedford Level, flooded year after year, to the extent of 100,000 
acres, whilst paying annual drainage taxes for security to the 
amount of 100,000/., sought relief in the opening of its river 
outfalls, and the mouths of the Nene and Ouse have been im- 
