BUILDING 



167 



FIG. 89. Sectional Elevation of Power House, Mississippi River Power Com- 

 pany, Keokuk, Iowa. 



heavily reinforced with I-beams and supported with concrete 

 piers. 



With horizontal turbines no basement is needed, although 

 tunnels are then, nevertheless, usually installed below the main 

 floor for cables, oil and water piping, etc. Ventilating ducts for 

 carrying fresh air from the outside to the different generators are 

 also essential, especially in low-head plants with slow-speed units. 

 This subject is treated more fully under " Ventilation." 



