I830.J 
17 
On the Tiles in the River Hugly , 
it is only 3ft.7in. by the diagram, a difference of only 6 inches for the influence of 
drainage upon the slope. With this allowance included the difference of the Janu- 
ary and August descent, by the mean path, cannot amount to 2 feet. 
Chart for August. 
In corroboration of what I have advanced upon the subject, I may add, that I 
have observed frequent instances of two tide creeks, proceeding from the selfsame 
mouth, approaching close to each other, after a long course (of 80 or 90 miles 
sometimes) , one perhaps with a freer channel, a more circuitous course, or more 
converging section than the other, and presenting very different tide phenomena, 
both us to the time anil quantity. The investigation in these cases invariably 
proved some trifling modification, if not in precise keeping with the above rules. 
The influence of such rules in the configuration and surface of such a district 
as the Sunderbunds, as also in its physical history, may well be conceived ; and it 
cannot be otherwise than interesting to trace the progress of the marine gulf 
into a lake with its inlets, the lake into a salt marsh,, and the salt marsh into a 
fen, only inundated in certain tides, and now fit for agricultural purposes. The 
tide is the moving cause in such changes, and a knowledge of the principles by 
which it acts is essential in the search. The configuration of the lower deltas 
of different rivers will be found to accord strangely with the nature of the tides 
which prevail in the seas before them. Thus, the disturbed and violent tides which 
prevail in the Bay of Bengal, accelerate the progress of lake into marsh, and marsh 
into fen; and the maritime lakes of the Mississipi delta, which have a depth of 15 
to 18 feet water, the tides of the gulf being only 4 to 5 feet, are replaced in the 
delta of the Ganges, before which tides of 15 or 20 feet prevail, by fens and salt 
marshes. It is also very easy to explain another curious circumstance in such 
countries, namely, that the country under cultivation, considerably inland, is seve- 
ral feet below the level of the land immediately on the coast, and yet by no means 
so liable to suffer from overflow, during extraordinary tides, unless their duration 
could he supposed to last a very unusual time. 
The level of the land formed by the deposits of the tide, in the same manner 
with the level of a river’s hanks, will be universally influenced by the high-watei 
mark, to which it ever bears a certain relation ; and if in the course of ages, by the 
gain of the delta upon the sea, the tides at any particular position have altered 
during that time, according as there may or may not be sufficient of sediment m 
the tide, will the changes in the level of the ground of that position be foun o 
have kept pace with the other change. . 
But 1 have said more than enough for some of your readers to form their own 
conclusions and follow up the subject. p 
Calcutta , 
December , 1829. 
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