142 EEMAEKS ON THE PROPAGATION OE SALMON 



EXPLANATION. 



A Water supply from cistern, constantly running. 

 u Plate-glass tank, containing artificially produced salmon-fry. 

 c c Pipes conducting water out of tank to model below. 

 D D Troughs in which ova are being hatched, filled with clean gravel. 

 D E Gratings through which water passes to gravel. 

 o Model of river containing salmon-fry. 

 H Weir across river. 



it Fish-pass over weir, to enable the fish to ascend to the upper waters without inter- 

 fering with the water power above. 

 jc Eiver below weir. 



