534 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 1923 



It will be noted from horsepower curves (fig. 6«) that up to cer- 

 tain maxima (198,000 for the 5.5:1 basins and 290,000 for the 2:1 

 basins) the available horsepower increases with an increase in the 

 hourly drop allowed in the high-level basin, but it must be borne in 



Hoyjr* - low Ttx> e -r+ t-o** tihe. 

 Fig. 66 



mind that as the hourly drop increases the maximum head decreases, 

 and the minimum head decreases more rapidly still; and we must 

 therefore select cases, such as has been done in the above table, that 

 can be successfully met by turbine operation. 



