dredges are considered adequate for all dredging requirements by 

 this Office. The Phleger gravity-type corer is satisfactory for most 

 reconnaissance-type coring operations. When long cores are required, 

 either the Kullenberg or Ewing piston-type corers can provide them. 

 However, it is recommended that the recently developed Hydro plastic- 

 barrel corer be used when less distorted, larger diameter cores are 

 needed for engineering analyses. It is not recommended that the Hydro- 

 graphic Office acquire a hydrostatic corer because of the distortion 

 caused to the sediment core as it is being taken. 



2. Continuous-profile subbottom equipment systems 



The Sonoprobe appears to be satisfactory for all shallow water 

 applications. The purchase of new equipment by the Hydrographic 

 Office at the present time is not recommended until apparatus recently 

 developed has been fully evaluated for suitability for the requirements 

 of this Office. Within a year, investigations of different gas explosion 

 sound sources and the Thumper may indicate the desirability of 

 acquiring one of these systems for routine survey work in deep water. 

 The Precision Graphic Recorder is considered to be more desirable 

 than the Precision Depth Recorder for use with continuous-profile 

 systems. 



E. SELECTED REFERENCES 



X-l. BECKMANN, W. C. Geophysical surveying for a channel tunnel, 

 New Scientist , vol. 7, p. 710-712, I960. 



X-2. ROBERTS, A. C, and LUSKTN.B. Sub-bottom depth recorder, 



Geo ph ysics , vol. 24, no. 4, p. 749-760, 1959. 



X-3. DIETZ, R. S. Methods of exploring the ocean floor, p. 194-209. 

 In; Isaacs, J. D., and Iselin, C. O'D., eds. Symposium on ocean- 

 ographic instrumentation, Rancho Santa Fe, California, June 

 21-23, 1952. National Research Council. Publication No. 309. 

 Sponsored by Office of Naval Research and National Research 

 Council. Washington 233 p. 1952. 



X-4. EMERY, K. O., and CHAMPION, A. R. Underway bottom sampler, 

 Journal of Sedimentar y Petrolo gy, vol. 18, p. 30-33, 1948. 



X-5. EMERY, K. O., and DIETZ, R. S. Gravity coring instrument and 

 mechanics of sediment coring, Bulletin of the Geolo g ical Societ y 

 of America , vol. 52, p. 1685-1714, 1941. 



X-6 



