1863.] FERGUSSON DELTA OF THE GANGES. 353 



towards the Swatch, it seems to have sufficient force to fix the 

 seaward limit of the western Sunderbiins as certainly as the current 

 that passes eastward has fixed the seaward boundary of the Delta of 

 the Nile. 



The eastern half of the delta is by no means so fixed in its 

 regimen, principally, I am convinced, owing to the cause pointed 

 out in a previous part of this paper — in consequence of the 

 Brahmapootra being diverted into the Sylhet Jheels, in which its 

 waters were filtered, and its consequently bringing no silt seaward. 

 We learn, however, from Lloyd's survey, made in 1836, that great 

 progress had been made in filling up the gap since the beginning of 

 the century ; and if we had a new survey now, we might prophesy 

 approximately how long it would be before the eastern face of the 

 delta would assume a form as fixed as the western half. 



The true base of the delta to seaward is the neutral ground 

 between the 5- and 20 -fathom lines, which there is no reason 

 to suppose has altered, or will alter, in any time of which we can 

 take cognizance ; for, the whole of the silt brought down by the ebb 

 being swept away to the depths of the ocean through the Swatch, 

 there is no reason to suppose that any sufficient portion of it is 

 brought back by the flood to alter so marked a boundary in any 

 appreciable degree. 



Inland there is another neutral line parallel to this, in the tract of 

 high land extending from Calcutta to Bakirgunge, and when the 

 delta is complete it will reach Seetacond ; this marks the boundary 

 where the tidal forces are stopped by the river's action, and where, 

 consequently, a certain deposit takes place. Behind this inland 

 barrier there still exists an immense tract of j heel- country, in the 

 districts of Jessore and Eureedpore ; but, judging from the extra- 

 ordinary changes which have taken place since Bennell's survey 

 was made, there seems no reason to doubt that, in the course of 

 another century, if the rivers are left alone, there will be very little 

 jheel-country left in the western half of the delta ; and the task of 

 the Ganges will then be completed, with the exception of a little 

 smoothing and filling here and there. But it will take several 

 centuries before the Brahmapootra will have rendered its domains, 

 especially in Assam and Sylhet, as habitable and as fertile as the 

 whole of the valley of the Ganges is, even at the present day. 



§ Y. Appendix. 



The following Table, though constructed on the best available 

 data, can only be regarded as an approximation to the truth, no 

 surveys having been undertaken with reference to the objects in 

 view ; and though certain levels may be absolutely correct, they 

 do not give either the average height of the land or of the water, or 

 they give that only at exceptional periods. 



The first two are from Col. Cautley's survey for the Ganges- 

 canal; the next three from that for the East Indian Bailway, 

 and may be depended upon except as regards the correct representa- 



