available through commercial sources. This is particularly true with 

 regard to equipment for measuring long wave atmospheric and back 

 radiation and the extinction of light in oceanic water. 



The water clarity meter (photocell type) shows considerable promise 

 for transparency and visibility measurements in coastal waters. 

 However, continued collection and analysis of data shows that further 

 engineering is needed to obtain greater dependability and operational 

 simplicity from this instrument. 



Early fabrication of a photometer to be used as part of the proposed 

 geophysical data collection system is recommended. 



K. MARINE BIOLOGICAL SAMPLING 



Equipment available for marine biological sampling appears adequate 

 to meet present requirements of the Hydrographic Office. With increased 

 experience and added requirements, improvements in instruments 

 probably will be required. 



L. BOTTOM MATERIAL AND STRATA DETERMINATIONS 



Emphasis in the past has been on coring equipment designed to take 

 long cores of relatively small diameter. Larger diameter, less distorted 

 cores are needed for engineering tests now required by the Navy. 

 Experimental use of coring equipment modified to meet these require- 

 ments is being made by the Hydrographic Office. Development is being 

 planned for certain in situ measurements which appear necessary to 

 completely eliminate disturbance effects induced by coring. 



Extensive inquiry has been made into the relative merits of instru- 

 ments which have been used to determine sediment thickness and 

 structure by means of essentially continuous-profile seismic reflection 

 techniques. Some of these instruments are still under development 

 or modification. Evidence to date indicates that of the existing devices 

 the Seismic Profiler of the Woods Hole Oceanographic Institution and 

 the Subbottom Depth Recorder of the Lamont Geological Observatory 

 are best suited to Hydrographic Office requirements when used with 

 the Precision Graphic Recorder. Since these systems are self- 

 contained and portable, they have the added advantages that they may 

 be easily shifted from ship to ship as need directs and that they are 

 easily serviced. It is recommended that one of these systems be 

 acquired and tested by the Hydrographic Office. 



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