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before reaching the sea is joined by the river Brahmapootra, a river as large as the 
Ganges itself. Many miles however before reaching the sea these great rivers are 
split up into several branches, on one of which the Hoogly, stands the important 
town of Calcutta. 
It is not an easy matter to fix the point where the delta begins ; it 
is however stated that the delta of the Ganges begins about 216 miles in 
a direct line from the sea, and the delta of the Brahmapootra 224 miles from the 
sea; these deltas it must always be remembered have long ago coalesced to form 
but one, which has a great number of mouths; we may say then that the com- 
bined delta of Ganges and Brahmapootra begins about 220 miles from the sea, that 
is a distance equal to that from Hereford to Newcastle-on-Tyne, and nearly equal 
to that from Aberystwith on the Welsh coast to Lowestoft on the East coast. 
The breadth of the delta is about 200 miles, and as it is as wide 220 miles from the 
sea as it is at the coast, the area of the delta will be about 4,400 square miles. 
The amount of sedimentary matter in the united waters of the Ganges and 
Brahmapootra has been estimated at x part of the water in bulk during the four 
56 
months of rains, when the discharge of water is estimated at 494,208 cubic feet per 
second, and this gives 577 cubic feet of mud discharged in a second. The rains 
last about four months, or 122 days, and therefore the total discharge of mud 
during the rains is, 6,082,041,600 cubic feet. The quantity of mud discharged 
during the eight{dry months is estimated at 286,035,840 cubic feet, so that the 
whole‘annual} discharge is 6,368,077, 440 cubic feet. This amount of mud would 
raise a surface of 2284 square miles one foot. When we consider: for what count- 
less ages this action has been going on we cease to wonder at the effects produced, 
and we recognise the importance of running water as a soil forming agent. 
I might here remind you that the sediment brought down by the Ganges, 
comes chiefly from the Himalayas upwards of a 1,000 miles distant. 
This one case out of many must suffice to show us the great power of 
water, for it is only the principle that we are engaged with at present, and we 
cannot delay over many examples. I may say, however, that anyone who likes to 
take the trouble to study the subject of deltas and alluvial formations for himself 
will be amply repaid. 
I must now pass on to the second case and explain how beds of different 
materials lie interstratified with one another. The power of running water to carry 
matter along with it depends upon its velocity, and when its velocity is increased 
then its power of transportation is increased also. 
The law of the transporting power of running water may be thus stated :— 
“The power of water to move bodies that are in it, increases as the sixth power of 
the velocity of the current.” (See Jukes’s Geology). 
Thus if we double the velocity of a current its motor power is increased 
64 times (26)=64; or, in other words, if a stream moving at a velocity = A was 
increased to a velocity = 2a, and if at rate A it could move a body of 1 lb. weight, 
