560 



MACHINES, WORK, AND ENERGY 



of the nozzle was but J^ in. and yet the wheel did 100 horse- 

 power of work. The efficiency of impulse wheels is frequently 

 80 or 90 per cent. 



FIG. 347. Vertical cross section of the turbine pit 



^ 



FIG. 348. Horizontal cross section of the turbine pit. 



668. Turbine Wheels. TURBINE WHEELS are now generally 

 takin'g the place of the older types of wheels. The water 



