1863.] FERGUSSON— DELTA OF THE GANGES. 345 



when Rennell surveyed Purneah, he saw, and recorded in his memoir 

 in the 'Philosophical Transactions'*, as well as in his Atlas, that 

 the Coosy had at no distant date flowed past the station at Purneah, 

 and joined the Ganges forty-live miles further down than its present 

 junction. Buchanan Hamilton not only confirms this, but adds : — 

 ** This tradition is not only supported by the above-mentioned 

 appearance, but by the opinion of the Pundits, or natives of learn- 

 ing, who inhabit its banks. These, indeed, go still further, and 

 allege that in times of remote antiquity the Coosy passed south-east 

 by where Tajpore now is situated, and thence towards the east till 

 it joined the Brahmapootra, having no connexion with the Ganges ; " 

 and he adds, " this opinion seems highly probable " f. Indeed, an 

 attentive study of the successive changes that have taken place 

 renders this almost certain ; and it is probable that the Oorasagur 

 is the mouth by which the combined waters of the Coosy, the 

 Mahanuddee, and the Attree were originally discharged into the 

 Assam river. 



Were it possible, it would be extremely interesting to know 

 when this was the case. We may certainly assert that it was before 

 the Madoopore jungle was upheaved — and when, consequently, the 

 course of the Brahmapootra was very nearly what it now is — and also 

 at a time when the tide, or at least very low land, extended to 

 Pubna or thereabouts ; and that this should have occurred within the 

 very limited range of the traditions of Lower Bengal induces me to sup- 

 pose that the beginning of the Christian era is the highest antiquity 

 that can be ascribed to such a state of things. It may be much later. 



The present course of the Coosy is so nearly perpendicular to that 

 of the Ganges, that its direct junction can hardly travel more than a 

 mile or two further up stream. The first result of any further rise 

 in the level of the Ganges will be that of decreasing the radii of its 

 curves, making it more winding, and converting it into a depositing 

 stream, which it hardly is at present 



The rising of the deltaic plain has already produced another effect 

 since llennell's survey was made, the middle, or the belly, of the 

 river having travelled westward some four or five miles throughout 

 the greater part of its course ; and it shows a great tendency to go 

 further in this direction — in fact, to emulate the example of its old 

 confluent, the Mahanuddee, which forms a curve extending thirty- 

 five miles to the westward of the straight line in which we may 

 reasonably suppose it reached the Ganges at no very distant date. 



As just mentioned, its junction with the Ganges tends to assume 

 the rectangular form explained in fig. 6 ; and though its main 

 course is steadily travelling westward, its mouth may travel east- 

 ward ; and, before many years are over, it probably will again join 

 the Ganges as low down as it did when its main stream flowed past 

 the station of Purneah. 



The principal river of the Tirhoot district is the Bogmutty, which 

 presents exactly the same phenomena as those last described. It 

 has an old bed to the eastward, much more perpendicular to the 



* Vol. lxxi. p. 87. t Martin, vol. iii. p. 15. 



