
Vol. IV,:Nos9j. . The Kosi River. 475 
(N.S. ] 
The waters are undoubtedly helped by wind and weather, but the 
main levelling agent must be the silt they carry. 
t has been stated that changes in river bed are the probable 
cavses of such undulations as occur in the neighbourhood of the 
osi River; bir explanation of this is en gt to the views of 
many who have written on the su ubject, but mind it is so 
imple a Logical, that I take the liberty a oadeag forward my 
ow 
ors us assume that the river has for some years occupied one 
bed and that it has raised that bed and its banks considerably ; at 
a time of rising flood,a tree trunk, sunken boat, orsome such obstacle 
becomes er ge in one bank of the river and forms, on its up-stream 
in eating a ceca through the bank. When once a reach is 
effected, a change in the direction of the whole pated may occur ; 
iT 
low lands on the side on which ah reeset 6 te oaanieili after 
doing an enormous amount of damage, eventually, let us say for 
argument’s sake. takes a new course parallel to the old one, 
half a mile to the east; it is possible to conceive a series of stich 
moves, which will leave ridges along which the river recently ran, 
and depressions between each two ridges, in which, for many 
centuries, no river bed has existed. In course ee time winds, rain, 
first sight this theory appears amabiae A little 
i nee here 
constructive river in the world obeys. The | aw may 
briefly as follows :— “ A constructive ee by the 
silt, eraiuallied sala its grade, or fall per mile, starting trim 
the point most distant from its source and ecu the 
reduction in grade up stream ” — the building up of the portion of 
British India icvalead has therefore commenced near the Ganges 
and is slowly invading the whole plain northwards, the rate of 
progress eens on many things which require some 
oO 
eye ahs 
Diagram No.2 is somewhat similar to a diagram given by 
7 eceeeeon. in the note already refe to. Itisa aeaparan 
betw: 
nnell’s survey and Survey of India maps up to date 
“the diagram shows that in 1780 the Ganges and Brahmaputra 
operated in certain areas in the plains ; about a century later, very 
- great changes have occurred, the Tista, instead of being a tribu- 
