204 
On the Snlt-TVatcr Lakes 
[JulV 
per hour, with a rate of 739.5 feet (about one-seventh of a mile per hour). This is 
even much beyond what I can believe to be true. The discharge of water from all 
the compartments of the lake, takes place rather by spilling over the banks of the 
outlet channel, (which have been raised to a level sufficient to be laid bare in th 
low tides of the dry season, by the silt left on them by the continued flux and reflux 
of tide,) rather than through any more defined side outlets ; and it therefore 
becomes difficult to measure the exact quantity of general expenditure from the 
whole lake in any state, except by an estimate from the dimensions and rate of this 
outlet, which is subject to a reflux in all cases 9 . 
That the lakes, if left to themselves, would, in the course of time, fill up of their 
own accord, I have little doubt ; and that such process is now in activity is con- 
firmed by the rapid increase of vegetation upon its surface within my own know- 
ledge. I cannot, however, learn that much ground has been gained to cultivation 
during the last forty years ; and although the amount of yearly filling up must at 
the present time be much greater than it was forty years ago, another period of 
this length will probably, unless other means are provided to increase the yearly 
sediment, witness a very sorry progress towards their final recovery. Unfortunate- 
ly', during the present state of things, the influx of jhtl water, although much of it 
is originally derived from the colored waters of the river Hoogly, brings little or 
no sediment ; and as the water is quite clear before it reaches the channel of outlet, 
its discharge checks at this time any silt from the daily tide, and also washes 
away much that may have formed during the dry months. 
The two principles, therefore, upon which. I would rely for a more effectual 
recovery of the lake, and of this compartment in the first instance, are, to prevent 
the influx of any water, but tide-water, that does not proceed directly from the 
Hoogly, or from a source whence sediment is certain, as from the drain outlets ; 
and to encourage the growth of vegetation along the banks of the present channel ; 
until, by this means, in the course of a very short time, it will be easy to form a 
slight embankment at small cost, and over which the water may still occasionally 
spill. 
The quantity of river water to be admitted (and consequently the dimensions of 
the feeder canal) must then be regulated by the heighth of the waters in the lake, 
which may at any time be lowered by a slight check to the feeder canal, by which 
means the discharge will gain upon the supply^ I would propose that the waters 
of this compartment of the lake be kept at an average additional elevation of less 
than one foot, which would injure no property in the vicinity ; or what would perhaps 
be still more perfect, that the supply be let in during the neaps, and so restrained 
in the springs, that the lake near Baliaghat shall remain at a constant level, of 6 to 
9 inches above its present extreme ; it now varies a foot during springs and neap 
height. 
I will now consider whether a feeder of 100 or 200 square feet of section, and 
excavated in a way that would secure it from accident, or from endangering the 
vicinity, would ensure a sufficient supply for this purpose, and what quantity of 
sediment might be looke d for during the year Avith this one feeder. 
The surface of this division of 5.5 square miles, at an average depth of 2 feet, will 
give its contents of water 306 662 400 cubic feet. The contents of the adjoining 
division must be about double this quantity'. Now a feeder canal of 100 feet 
section, trapezoidal, having the slope of 1 foot per mile, will run at a velocity of 
1.2 mile per hour, and supply* 634 600 cubic feet only in that time. Increase the fall 
of the surface of this feeder to 2 feet per mile, and with the additional section 
gained irom its trapezoidal shape, the rate becomes 2.4 miles per hour, and the 
supply 2 191 614 cubic feet per hour. I should not think it advisable to exceed 
this velocity. 
For the months, July, August, and September, I may safely reckon, from the 
known slate of the tides (and with allowances for closing the feeder when the river 
is too high, &c.) upon a medium supply of 900 000 c. ft. per hr. for 12 hours of 
each day, lhis supply (900 000 x 12 ~ 10 800 000 cubic feet per day) would 
fui rush a quantity equal to the present contents of this compartment 10 in 30 day's, 
exclusive of water brought from the drains and tide channel, and therefore I might 
leckou it possible to fill this compartment of the lake in the course of the rainy 
Section at Bahuiinghata 120 X 24 x 
. hour =20 375200 cubic feet, so t 
canuot be less than 50 000 000 cubic feet. 
30 V Suid bdore to be 300 400 cubic feet, and 306 662 400 -f- 10 800 000 = near! 
ner 1, (W - ru ia X f == 1020 sq. It. and 1920 X 5280 X 2 mill 
per hour _203/oA)0 cubic feet, so that when the lake is full the daily dischargt 
lO OOO cubic feet J 
