STONE PIEE TO PROTECT STRUCTURE. 



411 



SALMON LEAPS. 



the mill-power; but upon large rivers the plan is impracti- 

 cable. The same principle can be applied to a pass which is 

 imperfect, and it has been found to answer. A curving pier 

 has been built out from the dam below, so that the water 

 falling over the dam is thrown back by it, and though it is 

 open at one end, yet it passes far enough across the bed of 

 the river just below the fall to so raise the water that fish 

 get a start to leap the dam. To increase the depth of water 

 between this pier and the dam, a large beam of wood, in slant- 

 ing direction from the top of the dam to the pier, conducts a 

 wide sheet of water from the top of the dam to between the 

 dam and the pier. This method for a salmon-leap can not 

 injure the water-power. In all cases, the importance of such 

 vital means of assistance to the salmon requires that the arch- 



