1 830 .] 
in the vicinity of Calcutta 4 
205 
season, with four times its present contents of turbid water direct from the Hoogly, 
by means of a single feeder of the dimensions named. 
The proportion of sediment in the waters of the Hoogly is at present unknown. 
It is, therefore, impossible to say what would be the quantity produced from a 
depfeh of 8 feet water 1 l . Several inches may be expected; and if this be not thought 
sufficient, it is always possible to increase the supply, by enlarging the feeder or 
furnishing a second : for it is quite evident, that as the hourly supply of 2 000 000 
cubic feet is so small, compared with what I have estimated as the expenditure 
along this compartment of the lake (11 612 080 cubic feet per hour), and a daily 
supply of 10 800 000 cubic feet, so small compared with the daily discharge by 
the Bahmingh&ta outlet, that the rise of the surface in consequence of so 
trifling a supply will not be 6 inches. 
It will be said that the method I have now proposed embraces only one third of 
the whole lake ; but it must be remembered that it is the one of most importance to 
the town, and likely to yield the greatest return. The same feeders, when they have 
completed this portion, may be turned into the second compartment, and the self- 
same principle may be applied to the southern division, if thought necessary, by a 
feeder direct from the high parts of Tolly’s Nulla about Kalighat. 
The river Hoogly, it must be remembered, is the only source from which turbid 
w ater can be drawn, and this only during the four rainy months, 15th June to 15th 
October. The quantity of sediment in the Hoogly water will bear no proportion 
with that in the Ganges, and the tide waters of the Sundurbuns are notoriously 
clear during the rains, as also during the dry season, except in the spring tides, 
when they have inundated the land. 
I have already mentioned that during the rains there is a general slope of the 
surface of the lake, from the north towards the present outlet. To make this 
outlet the feeder, it would be necessary, to invert the present slope, or raise the water- 
-level near Baliaghat above what it is at present near Sambazar, which must un- 
avoidably interfere with the present drains. Besides, that by this means, as the 
present channel must be at once its supply and place of discharge, the supply, 
according to every sound principle, cannot be so constant and unremitted as if 
the supply were separate and at the upper end ; and no hope can be formed that 
the bed will be raised rapidly by any means but a constant introduction, during 
the rains, of river water. 
1 have purposely connected the present scheme with the system of canals now 
carrying on ; but upon mature consideration, I can see no g’ood reason why any 
alteration in those canals should be necessary for this additional object. The 
discharge canal must necessarily be the best adapted for navigable purposes, from 
its depth and tendency to deepen rather than fill up; and from its lower level it 
must be. fittest to receive all drain water. 
. ^ ^ * s said that no real efficacious method can be adopted until the whole lake 
is embanked, I need only refer to the very trifling additional rise of the surface 
ot the lake-waters necessary in the present scheme; and to mention that the 
adoption ot such plan will, in the course of a very short time, give the means of 
embanking at a very trifling expense, where now such a measure would be attended 
with very great charge and difficulty. 
If the circular canal is made the feeder of turbid water to raise the bed of the 
lake, it must unavoidably be subject to all the disadvantages which I have pointed 
out in a torrner paper upon that canal ; besides that other means must be provided 
to carry alt the drainage ot the town- This last point alone, in expense, would 
oppose a serious obstacle to such a measure. For as the only low level fit for re- 
ceiving the drain water will be, in this case, either the lake itself or the series of 
nalas eastward ot the lake, tunnels under the canal must be excavated, or a 
second canal ot sufficient dimensions must follow the line of the circular canal, 
and be continued perhaps to the very eastern boundary of the lake. 
By the present scheme, during the dry months, when the feeders no longer 
serve, the tide would be allowed as before to spread upon the lake, for I would by 
no means offer any check to this spreading. Here also would the action of silting 
up e accelerated, by the circular canal into which a higher tide and dirtier water, 
from its rapid passage through the canal, will flow from the river, and not be 
allowed to return. 
1 subjoin a table of the several levels, as referred to the tide guage, and a schedule 
or the method I would adopt for raising the bed of the lake. 1 feel some degree of 
confidence that the principle of this scheme, with perhaps some modification of 
i details, will, in the end, be acknowledged to offer advantages and economy 
eyond every other design that could be proposed for the purpose. p, T. 
1 1 Two feet average depth supplied four times = 8 feet of depth, 
