39 



Gvid oil the left, where detiecting a right angle to the righiV 

 it follows the base of the wall built to sustain the Chesapeake 

 and Ohio Canal. The other runs in a straight line between 

 two rock walls, with a width of about ibrty feet, and begins 

 at the transverse fissure about iive hundred feet east of where 

 Little River enters it. Both reach the main channel about 

 eight hundred feet below this point. 



The first place we examined, with a view of providing a 

 fish-way, was the location of the old Potomac Canal on the 

 Virginia side. But this being upon ground twenty feet 

 higher than the top of talis, and emptying into the river at 

 a point ten feet lower than their foot gave thirty ieet of extra 

 elevation to be overcome. And the distance where the nu- 

 merous locks were clustered, was so short as to preclude the 

 idea of making available any of the old work. 



Our next consideration was the erection of wooden iish- 

 vvays leading from tlie basin at the foot of the falls where the 

 .shad congregate in their baffled efforts to ascend higher, and 

 provided with the usual zig-zag or spiial compartments to 

 require the water to traverse a sufficient distauco to reduce 

 its velocity enough to be overcome by the fish. But when we 

 saw on every side, the clean and bare walls of rock, and the 

 rugged lodges where nothing had been allowed to remain, 

 except some immense boulders or some temporary deposits of 

 sand in protected hollows, it was easy to realize the power of 

 the Potomac, when its swollen fioods plunged over and 

 through them, and the grinding eftect of the glaciers Avhich 

 are so often driven before the accumulated water. We could 

 see no place where such unsubstantial structures could be 

 fixed without being brushed away like straws. It seemed 

 that the only practicable and secure passage-way for .ishad 

 wasj that v%'liich could be aiforded by cutting out of the rock 

 a channel having a rate of descent sutficiently moderate to 

 enable the fish to ascend. 



To ascertain the best mode and probable cost of accom- 

 plishing this, the engineers who accompanied us tranced two 

 lines with the transit, and found the elevations of the points 

 with the level. Both of these commenced at the dam of the 

 Water Works; one followed the edge of Falls Island to the 

 shad basin and byond, the other followed the course of Little 

 River to the point where the main volume deflecting to the 

 right, leaves the great transverse fissure. These lines witii 

 their profiles are laid down upon the map, which has been 

 made to illustrate your report. 



The basin where the shad are arrested, is so close to the 

 ledge from which the waters are precipitated, that any practi- 

 •eable grade could not be cut out from that point without an 

 Inordinate expense; as a grade ascending at the rate of four 



