SALMONOIDS AND TURBINES. 263 



by the net were as scanty, for out of fifty-two small and one 

 large Trout and two Perch, only a single crushed Perch was 

 obtained after twenty-five minutes' work. 



The experiments at Bushmills, while demonstrating the 

 dangers to Smolts, did not sufficiently show the fate of those 

 passing through the ordeal alive. As in former experiments, 

 both large and small Trout in the turbine-pit resisted the 

 suction downward. 



Turbines of other forms (such as the Alcott and Leffell), 

 standing in ordinary pits with a moderate fall, and with sixty to 

 eighty revolutions, have slight effect on fishes of the size of 

 Smolts. Even less active and supple forms, like Perch, escape 

 serious injury. A Parr as large as a Smoltmay be sent through 

 a turbine of this kind three times without apparent diminution 

 of vigour. Such turbines usually have from fifty to one hundred 

 and twenty-five revolutions per minute. 



Where the water is pure, as at Stormontfield, a minute dead 

 fish or a fragment is readily perceived. The movements of the 

 living fishes are also conspicuous. In Ireland, on the other 

 hand, the tinted water (from peat-bogs) often considerably 

 obscures observation, even white boards, placed at the bottom 

 of a foot or two of water, giving little help in detecting small 

 fishes which, further, appeared to shun them. 



The net employed at Stormontfield had a central bag or 

 pocket, with a smaller mesh than that used in Ireland ; yet the 

 Lochleven Trout (of the size of Smolts) went through the larger 

 meshes at the edges (^ in. and f in.), and were only de- 

 tained by the sand eel-net placed across the stream beneath it, 

 and which was a strong white net, having apertures about 

 one-thirteenth of an inch. The paucity of the captures in 

 some cases in Ireland was clearly due to the small Trout 

 passing through the meshes of the net. While the active and 

 uninjured thus might escape through the net, at the edges, 

 or in some cases beneath it, the net retained dead fishes or 

 fragments. 



In performing such experiments the greatest care must be 

 taken in handling the Trout, or in capturing them in the stream 

 or in the turbine-pits with a ring-net, for injuries are thus often 

 inflicted. 



