400 REPORTS ON THE STATE OF SCIENCE, ETC, 
is just above Beeston Weir, near Nottingham, above which all the main 
tributaries join the river. 
Head- and tail-water levels of the eight main weirs across the Trent are 
taken three times daily by the Trent Navigation Company. The informa- 
tion is at our disposal at any time. 
2. Method of computing flows.—At the site the Trent is 280 ft. wide. 
An accurate cross-section has been taken, subdivided into 20-ft. vertical 
strips, fourteen subdivisions in all. At the centre of each subdivision, 
velocity readings are taken vertically, approximately at 18-in. intervals. 
The mean velocity is computed from the plotted velocity curve for each 
subdivision, the total discharge being the sum of (area X mean velocity) 
for the fourteen subdivisions. 
This series of observations is to be taken at all water levels to obtain a 
rating curve to cover all stages from low summer level to flood level. 
Knowing the head over the weir crest for each calculated discharge, 
constants for the weir discharge can be obtained. 
The instrument used is Troughton & Simms’ ‘ Improved Current 
Meter.’ 
3. Keeping of water level records (near gauging site).—It is intended 
eventually to establish rating curves for the principal tributaries near their 
junctions with the Trent. On computing the rating curves, automatic 
recording instruments to give discharge of river at any water level will be 
installed at the various gauging sites. 
APPENDIX D (2) (d). 
GREAT OUSE CATCHMENT BOARD. 
(REPLY TO QUESTIONNAIRE.) 
By O. Borer. 
1. River flow gaugings—I have found no record of past -discharge 
observations. The only discharge observations made by me were at 
Bottisham Lock, and for the lock gate sluices I used the formula 
Q = -62A V2gh (Love’s Hydraulics). 
and for the drowned weir— 
Q=L [3-1 {@ +h) A) + 6-4ah +2] 
(Love’s Hydraulics). 
I have not yet taken any river discharge observations, but we shall do so 
in the Marsh Cut, where we are having a gauging site arranged. 
The site selected has a straight uniform reach of 14 miles in length, and 
we are fixing gauges at each end and in the centre. We shall read the 
surface slope from the gauges and take direct discharge observations at the 
centre by— 
(a) Surface floats, using the formula 
V= 
PN ER where V_ = the mean velocity, 
V, = the maximum surface velocity, 
and C is Bazin’s coefficient for the H.M.D. 
(6) By means of velocity rods, floating vertically in the stream and so 
giving the mean velocity in the vertical plane. 
