Acknowledgement 



We should like to thank Dr. J. B. Hersey for his advice and 

 assistance in the preparation of this paper. 



REFERENCES 



Dow, W, and S. L. Stillman, (1962) Inverted Echo Sounder. Marine 

 Sciences Instrumentation, Vol. 1, 263-272 (Plenum Press Inc. , New York). 



446 



