VOL. LXXI.] PHILOSOPHICAL TRANSACTIONS. 43 



change that I have noticed ; a mile in 10 or. 12 years being the usual rate of en- 

 croachment, in places where the current strikes with the greatest force, namely, 

 where 2 adjoining reaches approach nearest to a right angle. In such situations 

 it not unfrequently excavates gulfs of considerable length within the bank. 

 These gulfs are in the direction of the strongest parts of the stream ; and are, 

 in fact, the young shoots, as it were, which in time strike out and become 

 branches of the river ; for we generally find them at those turnings that have 

 the smallest angles. 



There are not wanting instances of a total change of course in some of the 

 Bengal rivers. The Cosa River, equal to the Rhine, once ran by Purneah, and 

 joined the Ganges opposite Rajemal. Its junction is now 45 miles higher up. 

 Gour, the ancient capital of Bengal, stood on the banks of the Ganges. Ap- 

 pearances favour very strongly the opinion, that the Ganges had its former bed 

 in the tract now occupied by the lakes and morasses between Nattore and Jaffier- 

 gunge, striking out of its present course at Bauleah, and passing by Pootyah. 

 With an equal degree of probability, favoured by tradition, we may trace its 

 supposed course by Dacca, to a junction with the Burrampooter or Megna near 

 Fringybazar; where the accumulation of two such mighty streams probably 

 scooped out the present amazing bed of the Megna.* 



In tracing the sea coast of the Delta, we find no less than 8 openings ; each 

 of which, without hesitation, one pronounces to have been in its time the prin- 

 cipal mouth of the Ganges. Nor is the occasional deviation of the principal 

 branch, probably the only cause of fluctuation in the dimensions of the Delta. 

 One observes that the Deltas of capital rivers, the tropical ones particularly, en- 

 croach on the sea. Now, is not this owing to the mud and sand brought down 

 by the rivers, and gradually deposited, from the remotest ages down to the pre- 

 sent time ? The rivers are loaded with mud and sand at their entrance into the 

 sea ; and the sea recovers its transparency at the distance of 20 leagues from the 

 coast ; which can only arise from che waters having precipitated their earthy par- 

 ticles within that space. The sand and mud banks at this time, extend 20 miles 

 off some of the islands in the mouths of the Ganges and Burrampooter ; and 

 in many places rise within a tew feet of the surface. Some future generation 

 will probably see these banks rise above water, and succeeding ones possess and 

 cultivate them ! Next to earthquakes, perhaps the floods of the tropical rivers 

 produce the quickest alterations in the face of our globe. Extensive islands are 

 formed in the channel of the Ganges, during a period far short of that of a 



man's life ; so that the whole process lies within the compass of his observation. 



« 



* Megna and Burrampooter are names belonging to the same river in different parts of its course. 

 The Megna falls into the Burrampooter ; and, though a much smaller river, communicates its name 

 to the other during the rest of its course. — Orig. 



G 2 



