Trunk Drainage. 
61 
carry off leakage and floods, and where there are not mills to hold 
back the water, the staunches, as now constructed, cause greater 
evil ; their sectional area, when fully open, being generally suffi- 
cient to pass only 6000 cubic feet per minute, or less than one- 
eiqhtk of the discliarge rendered necessary with moderate rain. 
In the absence of any embankments to retain the river, sufficient 
to deserve the name, and with utterly inadequate overfalls lor the 
escape water not wanted by the mills, the river teems over its 
brinks in all directions with a very small augmentation of its 
waters. In December 1848 a survey was made of all the mills, 
the heights to which the water was impounded, and the quantities 
running to waste over the sills, and the facts thus enabled to be 
calculated for four different places (by the author of a valuable 
but anonymous Report on the subject) are as follows : — 
Cubic feet of 
Place of Observation. 
Drainage Area. 
Water running 
Acres. 
to waste by 
Overfalls. 
245,180 
4,900 
2(57,112 
9,600 
300,000 
3,540 
Cotterstock Mill .... 
320,000 
29,332 
The enormous discrepancy of the quantities running off, com- 
pared with the areas of land draining to each point, indicates the 
amount of water which must be finding its way in other and 
illegitimate directions. Again, as the foregoing takes no account 
of the water passing the mill wheels, or the absolute quantity of 
water, we have a stronger illustration in the computed discharge 
of water at four successive mills, during a time when the river 
was quite full, but not actually in a state of flood, from observa- 
tions made in June, 1843 : — ■ 
Estimated flow 
Discharge by 
of river, at one- 
overfalls, mill- 
Mills. 
Drainage Area. 
Acres. 
eiglithof an inch 
in 24 hours' Bow- 
wheels, and 
sluices. 
ing down. 
Cubic feet per 
minute. 
Cubic feet per 
minute. 
157,000 
49,000 
11,054 
157,000 
49,000 
9,244 
170,000 
53,000 
5,386 
Castle Ashbij stream falls 
in, alone .... 
13,200 
4,000 
Wellingborough IMill .... 
176,000 
55,000 
11,655 
It will be seen that Doddington Mill passes 5668 cubic feet of 
water per minute less than Barton Mill above, although in fact it 
