Two methods were used to attain the desired wave period by adjusting 

 the speed o£ the varidrive. The first method was to operate the complete 

 generator system with the basin drained, and adjust the speed of the vari- 

 drive until the generator bulkhead motion was set at the proper period. 

 The second method was used when the basin was filled. The transmission 

 gear settings gave a speed reference shaft-to-crankshaft ratio of 3 to 1. 

 Therefore, the varidrive could be adjusted to the proper speed using the 

 speed reference shaft (60 revolutions per 38 seconds for the 1.90-second 

 period), while the generator blade could be left stationary by not turning 

 on the a.c. motor and amplifier. The first method was preferred because 

 the entire system could be checked out before starting the experiment. 



65 



