Vol. V, No. 10.] The Rivers of Bengal. 399 
[N.8.] 
margins. That is, the stream in its natural condition is 
already to some extent embanked. This is due to the deposit 
of silt from the water flowing out of the stream over its sides. 
think, therefore, that it is not an undue interference with 
natural conditions to add an artificial embankment of mode- 
rate height. We must, however, keep clearly in view the 
necessity of ascertaining what capacity the embanked channel 
will have for the passage of floods, and when, as is generally 
the case, tle capacity decreases as we proceed down stream, 
overflows have to be allowed at suitable places. 
t roblem were limited to making provision for the 
passage of certain determined volumes of water it would be com- 
paratively simple. What makes it much more difficult is the 
addition to the water of the mixture of sand and earth, 
the passage of water and silt over the banks generally, the 
relief is frequently found by means of gaps or breaches 1n the 
