Figure 2. --Piezoelectric transducer mounted in the end plate 

 of the experimental tank . The expansion and contraction of 

 the crystal elements, when energized, creates the sound or 

 pressure waves. These waves are transferred into the water 

 through the front of the "can" which is of thin flexible metal. 

 The "can" is filled with castor oil for more efficient expansion 

 and contraction . 



