THE FLOOD OF 1 843. 79 



measure, as the stream increases in depth, supposing the velo- 

 city to remain the same? If that be true, it must be per- 

 fectly apparent, that a point will be reached where the diffi- 

 culty experienced by the deep water in passing over the 

 obstruction will be so great that the obstruction itself must 

 yield its position, and be carried down the current. 



In passing over the same descent, the increase in velocity 

 which a stream acquires as it becomes deeper, is, no doubt, 

 very considerable, and full allowance for this should be made 

 in explanation of the fact, that these heavy materials are 

 usually deposited at points where the water is diminished in 

 depth ; but it should also be borne in mind, that this increase 

 of velocity is much greater at the surface than any near the 

 bottom of the stream — the velocit)' alwa^'S being the least at 

 the bottom. 



The friction of the water over these ponderous obstruc- 

 tions is another ingredient which must be taken into account 

 in explaining their transportation. Loaded as the water is 

 with heavy sediment, during the time of a great flood, with 

 its depth and velocity greatl)' increased, its friction on the bed 

 of the stream, or upon obstructions resting on the bed, must 

 be very considerable. In fact it is onh' necessar}- for the fric- 

 tion of the water in passing over an obstacle, to exceed the 

 friction the body in moving would have on the bed of the 

 stream, to insure its transportation from this cause alone. It 

 will be difficult to explain the removal of certain thin, flat 

 stones of considerable dimensions, which actuall}' took place, 

 without taking this item of force largely into the account. 



To enter into a full detail of all the facts under this head, 

 which came to the knowledge of the committee, would be 

 tedious and uninteresting, and could answer no valuable 

 purpose. In the details of the flood which have already been 

 given, sufficient evidence was exhibited of its tremendous 

 foi^ce, in the sweeping awa^' of mill dams and bridges, of 

 mills and dwellings, and in the uprooting of many trees, and 

 the disseverance of the massive trunks of others. The com- 



