158 Silt held in suspension by the Hooghly. [No. 2. 



Feet. 



Mean depth, 29.102 



Mean velocity per second, 35.562 



Discharge per second in gallons, (Imp. measure ?) 3.214.758 

 Which is in Cubic feet, H. P., 507.060 



Col. Goodwin estimates the discharge at Calcutta 



to be per second, Cubic feet, 444.960 



At one inch of solid matter for every cubic foot 

 of water, this would give, for the Moyapore 

 average, per second, cubic feet of silt, 298. T 8 T W 



For the Calcutta average, cubic feet of silt, .... 257. T 8 T 9 2 4 s 



The mean of these two we may call in round 



numbers Cubic feet per second, of silt, 278. 



Or per hour, Cubic feet of silt, 1.000.800 



Or per day Cubic feet, 24,019,200 



* I copy the following from the work of Mr. Charles Ellet, Junr. ** On the 

 Inundations of the Mississippi and Ohio Rivers," (p. 173) published in 1853. 



44 The quantities of earthy matter contained in the water of the Mississippi in 

 different conditions of its surface, have been investigated by several scientific 

 gentlemen, whose results are not widely different. Preference is here given, how. 

 ever, to those published by Professor Riddell, of New Orleans, who, to his scien- 

 tific reputation and skill as a manipulator, has superadded the claim to confidence 

 which is due to great zeal in this subject. 



** The experiments of Professor Riddell have led to the conclusion, that the pro- 

 portion of sedimentary matter to the weight of Mississippi water containing it, is 

 as follows. 



Water 1 ; maximum weight of sediment ^-|^- 



Water 1 ; mean weight of sediment ~^-g 



Water 1 ; minimum weight of sediment 23V0 



** When solidified into coherent earth, at a mean, it was found that the bulk of the 

 sediment was equal to the ■g-oTTo part of that of the water in which it was sus- 

 pended. 



'• But the greatest amount of sediment is found when the river is in flood ; and it 

 is when in that condition that the discharge into the lake would take place. We 

 may assume, therefore, from these experiments, that when there is a great flood in 

 the river, the bulk of sediment would be to that of the water containing it, about 

 as 1 to 1800." 



