14 
MIDDLE LIAS OF NORTHAMPTONSHIRE. 
Jan., 1889 . 
The real scour of flood water only occurs when the water 
is sufficiently high for the overshots, &c., to offer no serious 
impediment to its discharge, and then it scarcely affects the 
bed of the river, although it often does great damage to the 
banks and adjacent lands. The Nen from Northampton to 
Kislingbury, and from Northampton to Brampton, was cleaned 
out a few vears since at a cost of about £1,500; also a small 
portion of the latter branch, near to the Castle Station, was 
straightened, being a necessary work in connection with the 
loop line of railway between Northampton and Rugby. 
These works have not prevented floods in the meadows west 
and north of the town, but none have occurred in the town 
itself since they were done. I doubt, however, whether any 
real trial of the improvements has occurred. 
4.—Artificial Obstructions. — Several of these have been 
briefly referred to already, but one or two require particular 
consideration. 
Mills and their necessary weirs do tend to hold back 
Water, and keep rivers nearly bank-full, with the result that 
floods are more easily induced. Complaints against millers 
and mills have been pretty continuous for a great number of 
years, and deservedly so perhaps, though mills need not be a 
cause of floods. The complaints are chiefly in respect to the 
excessive height of the floodgates and weirs, but sometimes 
on account of negligence in connection with the regulation of 
sluices and locks. There is always a tendency for mill-dams 
to get higher, for, supposing any impediment to the free flow 
of water to exist in the lower parts of the river, this will 
increase the height of the tail water at the mill next above. 
The result of this is that the miller here finds it necessary, in 
order to get the same power, to raise his head of water, but 
if he does not at the same time raise his wheel, he must raise 
the head more than the tail is raised, in order to overcome 
the resistance of the dead water; and so the banks are 
heightened, and possibly flash boards put up at the weirs, 
and it has happened that ancient weirs and back-brooks have 
been stopped. When this kind of thing is done at one mill, 
it must be repeated at the mill next above, and so the evil 
increases. A survey, made by Mr. Aris in 1826, showed that, 
owing to these operations, the water was raised between 
Thrapstone and Nun Mills, Northampton, twenty-three feet 
altogether above the legal height as ordered by the Com¬ 
missioners of Sewers (9tli Charles I., 1633).* 
* See “Drainage of the Nene Valley,” by the Rev. Charles Henry 
Hartsliorne, 1848. 
