SALMON OIDS AND TURBINES. 261 



either kept the turbine-pit, or probably passed by the head- 

 race upward through the 2-in. spaces between the bars when it 

 was in their power to do so. The smaller Trout also refused in 

 many cases to leave the turbine-pit, even though long rods were 

 moved in the water to drive them downward to the turbine. 

 They preferred the gently moving water of the pit to the vortex at 

 the edge of the turbine or the flow from the head-race, yet when 

 they had the shelter afforded by the wooden trunk or tube in the 

 midst of the pit, they chose it, and hence the numbers present 

 when the trunk was drawn out. As the head of the chimney- 

 sweeper's brush was enveloped in cotton cloth so as to make a 

 rammer to fit the tube or trunk, and as it was kept in most 

 cases in position at the bottom till the experiment was finished, 

 it is clear that, as at Messrs. Hill's at Lucan, the Trout had 

 returned to the shelter of the trunk after removal of the rammer 

 a few minutes before being drawn up. The ramming of the 

 Trout out of the trunk directly into the currents rushing into the 

 turbine required care, so as to prevent the Trout gliding up- 

 ward above the plug of the rammer. It was best done slowly, 

 and with water poured in from above. In the first experiment 

 at Cullybackey the head of the brush was unguarded, and the 

 fibres injured the Trout (removing an eye), whilst the loose brass 

 end crushed others beneath it. The Trout readily rose above 

 the unguarded brush, and appeared at the surface of the water 

 in the trunk, and, even when guarded, unskilful use was followed 

 by the appearance of a few at the surface of the water in 

 the tube. 



Less active fishes than Trout pass out of the pit through the 

 turbine more quickly. Thus, for example, more than half the 

 Carp were caught in the net at Lucan in half an hour. Many 

 others probably escaped by the sides of the net, which could not 

 be closely fitted to the walls of the tail-race. These stouter, 

 stiffer fishes would have suffered more severely than the Trout if 

 the turbine had inflicted injuries on them. 



In reviewing the different forms of turbine, it would appear 

 that those of the type of the Hercules turbine, placed in a pit of 

 some capacity and with a moderate and free fall, have, as a rule, 

 comparatively little effect on Trout of a size approaching Smolts, 

 and, further, that fishes of a size considerably larger may pass 



