334 PROCEEDINGS OF THE GEOLOGICAL SOCIETY. [Apr. 1, 



Jennai. Having no earlier maps than those of Rennell, it is impos- 

 sible to be certain what the condition of this river was before he 

 surveyed it. He found it flowing due north and south, in one-mile 

 oscillations, with a breadth of between 400 and 500 yards, and 

 flowing so regularly that I cannot help suspecting that it was then 

 a very young river ; if I may be allowed to guess, I should say not 

 more than twenty years old. In fact, it seems to have been the first 

 product of the struggle between the Megna and the Brahmapootra, 

 and did not exist till the waters of the latter river had been dammed 

 back so as to flow in this direction. 



When Buchanan Hamilton visited this country in 1810, he merely 

 remarked that the Brahmapootra threatened to " carry away all the 

 vicinity of Dewangunge " (which it has since done), " and perhaps to 

 force its way through the Konnai (Jennai) into the heart of Natore."* 



It was not, however, till ten years later that it had increased to 

 such an extent as to affect the Jessore rivers ; and it was not till 

 about the year 1830 that any reliable information was obtained 

 regarding it. About that time a party of engineer officers was sent 

 to connect Assam with the Great Trigonometrical Survey then in 

 progress in Bengal. They carried a series of triangles up the bed of 

 that river ; and it was at the same time attempted to navigate it with 

 steamboats. Nothing, however, was published until the river was 

 laid down on a map of Bengal which I constructed, in conjunction with 

 the late Mr. Tassin, on a scale of eight miles to one inch, in the year 

 1836. At that time it was flowing through Natore with an oscilla- 

 tion of nearly seven miles, and has continued to do so ever since ; for 

 though in its oscillations it sweeps away hundreds of miles of land 

 every year, it is only very lately that it has shown any restlessness, 

 or any tendency to leave its present direction, and whether it will 

 be successful or not in so doing still remains to be seen. In the 

 meanwhile the river is nearly where it is shown on the map ; but, 

 as it was there in 1850-53, it certainly is not there now, as it 

 never is exactly in the same place for two successive years, being- 

 young and active, and roaming through a new and. unconsolidated 

 country. It may also be mentioned that the city of Serajgunge — 

 the largest and most important mart in that part of the country — is 

 somewhere in that neighbourhood now, but not where marked on 

 the map, of course, as it is annually obliged to accommodate itself to 

 the vagaries of the stream, and change its locality. It may be ten 

 miles further up the stream, or ten miles further down, or five miles 

 further east or west ; but it is somewhere thereabout ; and that is 

 all the information geographers can hope for in a country where 

 land can only be classed with floating capital. 



6. Jessore Group of Rivers. — The first result of this invasion of 

 the Gangetic territory by the Brahmapootra was, that it should 

 seek to re-enact the part which had just been performed on the other 

 side of the Madoopore Jungle and should threaten to shut up the 

 Ganges, and send it back through its own distributaries. It was so 

 nearly successful that, in 1838, the Great Ganges was fordable at 



* Martin, vol. iii. p. 396. 



