208 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1910. 



5 inches thick the proportion of cement and sand is 1 to 2£, respec- 

 tively, instead of 1 to 3, and stone for walls of less than 10 inches 

 thickness is screened and thoroughly separated, so that no stone in the 

 mixture may have a greater dimension than 2£ inches. 



From the power-house end of the dam, as shown on the chart 

 opposite page 200, there will be run an ice fender for protection 

 against logs and floating ice. This will be built upstream, curving to 

 a junction with the shore and will be 2.800 feet long. The material 

 will be concrete. The general design will be similar to that used by 

 Mr. Cooper in one of the Niagara Falls developments. To the eye the 

 fender will appear as a solid Avail fencing off the power house from 

 the river. There will, however, be large arched openings below the 

 water level through which the water will find its way to the power 

 house. 



INSTALLATION. 



In the initial development it is planned to install 15 main water 

 wheels of the Francis type pressure turbines with single runner 

 mounted on vertical shaft, so providing for direct connection to main 

 generators. These turbines are to have a normal output of 10,000 

 mechanical horsepower each at a speed of 57.7 revolutions per minute 

 and head of about 32 feet. The maximum output is to be approxi- 

 mately 13,500 mechanical horsepower under a maximum head of about 

 39 feet. The design of governors, gate control, main step bearing, 

 bucket design, and intermediate details incident thereto embody 

 features usual in hydroelectric construction. 



The main generators will likewise be 15 in number, of vertical 

 shaft revolving field type, each having capacity of 8,000 kilowatts at 

 normal rating with overload capacity of 25 per cent for two hours. 

 These generators are to deliver three-phase alternating current at 

 11,000 volts and frequency of 25 cycles per second. 



With the generators there will be installed initially two exciter 

 turbines direct connected to the generators. These turbines will be of 

 the same type as the main generator turbines, and will be mounted on 

 concrete foundations and will have the same type of water inlet and 

 discharge as provided for main units. The governors for main units 

 and exciter turbines will be of standard construction for hydraulic 

 regulation. Each turbine will be provided with an independent gov- 

 ernor direct connected to the turbine gate control. The exciters direct 

 connected with the exciter turbines are to deliver direct current to the 

 generator fields at a suitable voltage. 



Initially there will be installed step-up transformers of sufficient 

 capacity to deliver to the transmission lines, over and above the line 

 loss 60,000 electrical horsepower which has already been contracted 



