The sound division of the Naval Research Laboratory under 

 Dr„ Ho Co Hayes was active in the basic study of crystal vibra- 

 tions o NRL has differed from UCDWR in the philosophy govern- 

 ing this latter work. NRL has preferred the direct solution 

 of the differential equations with suitable boundary conditions 

 rather than the representation of the problem by an equivalent 

 circuit o It is highly desirable that both methods be followed, 

 the one to act as a check on the other „ The direct method is 

 somewhat more cumbersome to use, but when aided by a compre- 

 hensive report recently published by W, Jo Pry, J. M. Taylor 

 and Bo W D Henvis of NRL ("The Design of Crystal Vibrating 

 Systems") can probably compete for accuracy and speed with 

 calculations based on the equivalent clrcuito The method of 

 direct solution, however, lacks the convenience of the LCR 

 simulator „ 



44 



