APPENDIX. 319 



selected where most water flows over. In this trough are 

 fixed stout, transverse boards or steps, properly supported, 

 to resist the weight of the stream. Stone will be found 

 cheapest in the long run. These boards or steps do not 

 of course continue entirely across the trough, so as to 

 bar the fish out j but an opening is left at either side 

 alternately, through which the fish can rush. In fact the 

 stream, instead of being in one fall impassable to the 

 salmon, is broken up into many falls, each in turn being 

 easily passable. 



The accompanying diagram will illustrate the manner 

 in which this is contrived. The arrows denote the 

 direction of the stream, and it will be seen that behind 

 every step the salmon can find a safe resting-place. 

 When the fall is very heavy and perpendicular, it is 

 less expensive to make a cut round it, which is done 

 by digging a passage from some distance above it, as 

 close to the foot of the fall as possible, — this cut, of 

 course, being broken up by steps into a series of small 

 falls, easily practicable to the fish. This plan was adopted 

 at Ballisodare and at Lough Mask. 



IX. 



COBEGONUS LAVAEETUS AND EEEA. 



I GIVE here short descriptions by Dr. Carl Voght of the 

 above two fish ; not of course adopting those descriptions 



