eae Sl 1665 Vo, 406 16% RESEARCH AND DEVELOPMENT REPORT c REPORT 768 13 MARCH 1957 THE NEL TYPE Ill DEEP-SEA CAMERA C. J. SHIPEK U.S. NAVY ELECTRONICS LABORATORY, SAN DIEGO, CALIFORNIA A BUREAU OF SHIPS LABORATORY 892 Wodey /14N THE PROBLEM Investigate problems in sea-floor oceanography through suitably devised means, methods and equipments. This report discusses the development, design and use of the NEL Type Ill Deep-Sea Camera to study micro-relief features of bottom sediments. RESULTS The development of the camera provides an improved tool for the study of deep ocean- floor environments. At least twenty-four bottom pictures can be obtained on a single lowering of the camera to a depth of 20,000 feet from small vessels equipped with light winches and 3/16-inch-diameter wire lowering ropes. The compact, watertight arrange- ment of the camera, illumination unit, electronic flash tube, tripping switch and lowering frame has reduced the total weight to only 125 pounds in sea water. This has resulted in lower costs of operation, maintenance, and replacement. The wide-angle lens, faster film, and electronic illumination employed in the NEL Type Ill Deep-Sea Camera are producing sea-floor photographs of greater definition and better contrast. RECOMMENDATIONS 1. Continue investigation of methods of indicating bottom contact. Complete the development of an electro-mechanical device, to be attached to the dynamometer in the lowering equipment, to give good bottom-contact indications for water depths in excess of 12,000 feet. 2. Develop and package a camera with a wide-angle lens and larger film size to be used with a 300 watt/sec flash. 3. Investigate the use of correcting lenses and filters. 4. Investigate the availability, cost, and use of some form of plastic rope of neutral buoyancy for lowering the Type IIl Camera. Such a rope would also help to solve the problem of bottom indication. 5. Develop a direction control for the NEL Type Ill Camera to extend its usefulness in the solution of problems dealing with current direction, sources of material supply, and gradients of submarine slopes. ADMINISTRATIVE INFORMATION The work was performed under IO 15401, NE 120221-34 (NEL L4-1), from July 1954 to November 1955. This report was approved for publication 13 March 1957. The author wishes to acknowledge the assistance of E.L. Hamilton, R. F. Dill, and G. A. Shumway of the Ocean-Floor Studies Section and the members of the Mechanical Engineering Division who aided in the designing, drafting, and packaging of the NEL Type Ill Deep-Sea Camera. WML NN 0 0301 004055? CONTENTS 2 INTRODUCTION GENERAL DESCRIPTION OF CAMERA 3 7 OPERATIONAL INFORMATION 7 Selection of Subject Material and Field Coverage 8 Camera Settings, Film, and Optics 8 Field Illumination 9 Bottom Contact and Weight-Strength Relationships Between Camera and Lowering Rope 11 Maintenance and Care of Equipment 12 Limitations 12 APPLICATION OF THE CAMERA TO THE STUDY OF OCEAN-FLOOR ENVIRONMENTS 12 CONCLUSIONS 17 RECOMMENDATIONS 17 REFERENCES ILLUSTRATIONS page figure 3 1 NEL Type Ill Deep-Sea Camera 4 2 Camera and power supply unit in camera case 5 3 Camera and power supply unit 6 4 Schematic diagram of electrical units assembly 6 5 Schematic diagram of circuits of NEL Type Ill Deep-Sea Camera 7 6 Diagram of field of photographic coverage 9 7 Optics for NEL Type Ill Deep-Sea Camera 11 8 Plan view of a typical deck arrangement for lowering camera and indicating bottom contact 13-16 9 Underwater photographs of some typical sea-floor environments taken with the NEL Type IIl Camera TABLES page table 10 1 Weight-strength relationships for lowering NEL Type II] Deep-Sea Camera INTRODUCTION The increasing use of photography in studies of ocean-floor environments created the demand for a small, portable camera unit to replace the heavier, more cumbersome underwater cameras previously developed at NEL.! (See list of References at end of report.) Field exploration with the heavier cameras, one of which weighed over 2000 pounds, required the use of a vessel equipped with a strong winch, booms, and a heavy wire lowering rope. The lowering rope most widely used is of 3-by-19 stranded wire, 3/16-inch in diameter, with a breaking strength of 3340 pounds. The NEL Type Ill Deep-Sea Camera was designed for safe lowering on such a rope to a depth of 20,000 feet, and its over-all submerged weight in water is 125 pounds, which satisfies the applicable safety and working load requirements. GENERAL DESCRIPTION OF THE CAMERA The NEL Type Ill Deep-Sea Camera consists of a watertight arrangement of a spring-wound 35-mm robot camera, a 2000-volt electronic power source of commercial design, a flash tube in a clear plastic envelope which is mounted within a water-filled aluminum reflector, and a small oil-filled tripping frame of steel serves to hold the watertight case camera, flash unit, and electrical power supplies to the ocean floor.2? The watertight case which is switch (fig. 1). A rigid lightweight and junction box which house the in the proper oblique relationship mounted near the top of the frame is a thick-walled cylindrical tube of forged aluminum with an internal diameter of 9 inches and an internal length of 14 inches. It is equipped with a clear quartz port in the detachable head to allow the self-contained camera to look out. The illumination control unit and all necessary power supplies are packaged with the camera for more ALUMINUM ~ CAMERA CASE HEAD STEEL FRAME MICRO TRIPPING TCH PLASTIC ELASH TUBE ENVELOPE & FLASH TUBE SAFETY PIN Figure 1. LIFTING EYE ALUMINUM CAMERA CASE CAMERA LOOK-— THROUGH PORT '=—— HANDLES STAINLESS STEEL CONNECTING TUBE STAINLESS STEEL JUNCTION BOX TRIPPING LEVER SPRING LOADED FEE: FIXED TRIPPING LINE VARIABLE TRIPPING LINE LEAD WEIGHT NEL Type Ill Deep-Sea Camera. efficient operation, maintenance, and repairs (figs. 2 and 3). The stainless-steel junction box, located directly below the aluminum camera case and supported by the light steel frame, serves to hold the protected flash tube, aluminum reflector, and the oil-filled tripping switch. A thick-walled stainless steel tube connecting the box and camera case carries and protects the necessary electrical wires. A mechanical tripping device, which employs a free-swinging lead weight, is attached to the frame below the junction box to activate the electrical tripping switch. Operation of this switch by bottom contact at 30-second intervals permits at least 24 successive photographs to be taken on a single lowering of the camera. Figures 4 and 5 show the electrical components and self- explanatory circuits employed. Detailed plans and specifications of the equipment are available upon request. CAMERA CASE ROBOT CAMERA ap Bs 30MM LENS ‘CAMERA SHUTTER TRIPPING ARM CONNECTING TUBE JUNCTION BOX oe : Figure 2. Camera and power supply unit in camera case. 35 MM ROBOT CAMERA P-2 HEILAND WILCOX STROBOSCOPIC FLASH UNIT CAMERA SOLENOID BATTERY — CONDENSER UNIT Figure 3. Camera and power supply unit. CAMERA, SOLENOID, FLASH UNIT, BOTTOM CONTACT SWITCH, SOLENOID BATTERY, FLASH TUBE HOLDER & FLASH TUBE CAMERA FLASH TUBE V4x KEMLITE CAMERA PLUG SOLENOID 6 FLASH TUBE HOLDER | LUUMINATION UNIT | HEILAND | WILCOX P-2 | 2000 VOLTS | CONTAINS OWN | | | | POWER SUPPLY Fr 1 BOTTOM 2-2 VOLT | | CONTACT WILLARD ER-6-2B Loy SWITCH WET CELLS Figure 4. Schematic diagram of electrical units assembly. FLASH TUBE V4X KEMLITE POWER TRANSFORIMER POWER SWITCH SOLENOID 6V DC JONES SOCKET ROBOT CAMERA INTERNAL SYNC, SWITCH Figure 5. Schematic diagram of circuits of NEL Type III Deep-Sea Camera. OPERATIONAL INFORMATION Selection of Subject Material and Field Coverage Deep-sea photography with the NEL Type III Camera provides no pre-selection of underwater subjects for study. Critical areas for study or investigation are selected by latitude and longitude from existing bathymetry and navigational charts. Locations for lowering the camera are determined by geographical position and by depth to specified bottom features such as canyons, basins, escarpments, slopes, and ridges. Figure 6 shows how the variable tripping wire and weight are adjusted to the fixed tripping wire to give the desired subject distance, in water, of 6 feet, when the camera is preset with an angular divergence of 30° from the vertical. Assuming use of 35-mm film and a robot camera fitted with a lens of 30-mm focal length, the resulting field coverage will be an elliptical area 5.7 feet long by 4.7 feet wide, or approximately 21 square feet. A special scale is used to make measurements of detailed features within a 7¥2-by-7¥2-inch photographic enlargement when the degree of magnification and the camera-to-subject distance (after proper corrections for water refraction) are known. ANGLE a = 30.5° ANGLE B = 30.0 VERTICAL DISTANCE VERTICAL DISTANCE CAMERA LENS TO SEA FLOOR VARIABLE TRIPPING WIRE CAMERA FIELD DEPTH FIELD OF ILLUMINATION Figure 6. Diagram of field of photographic coverage. Successive photographs taken at regular intervals along the bottom provide field coverage over an area determined by the set and drift of the lowering vessel. Features made visible by the development of the photographs obtained are then studied to help reveal the nature of environments. The most efficient use of the deep-sea camera is obtained by proper planning of ship time in selected areas of study. Depth is still the primary factor in determining where photographs can be taken, how long it will take to get them, and how many can be obtained on a single lowering of the camera. Camera Settings, Film and Optics Camera settings are made in advance before each lowering when corrections for water refraction, turbidity, depth, picture size, and subject distance can be taken into consideration. A fast lens of short focal length has been used extensively in the 35-mm robot camera and has given highly satisfactory results.* A shutter setting of 1/25 second permits easy synchronization with the short (1/1500 second) duration of the flash and exposes the film properly for clear, sharp negatives. Tri-X film has been found most suitable for underwater use and is now employed almost exclusively for black-and-white bottom studies. It is a very fast panchromatic film of moderate grain, with wide exposure and development latitude, and provides maximum detail and depth of focus in the field of photographic coverage.° To correct for the higher index of refraction introduced by the air-to-quartz-to- water interfaces it is necessary to correct the true camera-to-subject distance for work under water. A standard rule for corrections is: set the lens for a distance equal to three- fourths the actual distance.* For normal use, at depths where no extraneous light is present, the lens is set at f8 for an apparent camera-to-subject distance of 6 feet; for more light the lens is opened to 6.3 and for less light stopped down to 11 or 16. High-speed Ektachrome film, Daylight, has worked well for color. For best results the camera lens is opened to f2.8 and the subject distance adjusted to insure adequate lighting on the subject. Field testing is recommended to determine the best camera settings to use at specific preset subject distances. Figure 7 illustrates the optical relationships between air, quartz, and water interfaces inherent in the design of the camera unit. The lens of 30-mm focal length has an angular field coverage of 57.6° in air. The net refractive effect of the clear quartz window (index of refraction 1.54) and salt water (index of refraction 1.33) narrows this angular field coverage to 42.4° which results in a loss of 15.2° field angularity.® Filters are not employed on NEL deep-sea cameras at the present time because of their absorption throughout the spectrum.’ Also, a large part of the photography being done with the Type Ill Camera is in deep water where turbidity is low. To place the camera closer to the subject in areas where the turbidity is high a wide-angle lens system can be employed.* Field Illumination A 2000-volt Heiland-Wilcox P-2 Flash unit and a Kemlite V4X flash tube provides flash illumination. Figure 5 shows the basic electrical circuits employed. The flash tube is enclosed in a clear plastic envelope capable of withstanding hydrostatic water pressures in excess of 10,C00 Ib/sq. in. The water-flooded aluminum reflector in which the tube is mounted is designed to provide illumination with a minimum of back scattering (see fig. 6). * See ref. 6, pp. 3-4. CIRCLE OF aaOETIES. GOOD DEFINITION ANGLE ~< = ANGLE @ ANGLE = 28.8° ANGLET, = 18.22 [, Fitm pias. ANGLET;= 21-2° 33MM ee QUARTZ PO is PAMERA ANcle{ IN A\R 420=57.6° THICKNESS ta" CA ER MERA ance IN WAT 42r, =42.4 Figure 7. Optics for NEL Type Ill Deep-Sea Camera. The Kemlite flash tube and those of comparable design give off light of a spectral quality approaching that of daylight. The short duration of the flash (1/1500 sec) will stop fast action and freeze normal camera movement. This results in pictures of sharp definition. Also, light from the flash tube provides the duration and spectral intensity required for color film.? The Heiland-Wilcox illumination is a repeating type capable of being operated at 15-second intervals. Figure 4 shows in schematic form how the electrical components are assembled to function with a 35-mm robot camera as a compact unit. For faster repairs and exchange of parts and batteries, matched Jones plugs have been utilized. To insure maximum light intensity, pictures are taken at not less than 30-second intervals. The flash unit is operated on a set of two 2-volt Willard wet cells wired in series. They can be recharged many times. Bottom Contact and Weight-Strength Relationships Between Camera and Lowering Rope Positive contact with the bottom is essential to successful sea-floor photography. Although there are various methods for obtaining contact, most are ineffective in depths exceeding 1000 fathoms. A simple yet effective slack-wire technique employed at the U.S. Navy Electronics Laboratory utilizes sensitive tensional changes in the 3/16-inch- diameter wire lowering rope to detect the moment at which the camera reaches the sea floor. The twenty-four possible bottom photographs can be taken aft intervals of not less than 15 seconds by raising the camera unit clear of the bottom between each activation of the tripping switch. Under normal weather and sea conditions this slack-wire lowering technique has been used successfully to 12,000 feet. The over-all design was made consistent with the limitations of the 3/16-inch- diameter, 3-by-19 wire rope used for lowering purposes. This size and type of stranded rope has become standard in many phases of oceanographic field work. A 20,000-foot length of this wire rope weighs slightly over 1100 pounds in sea water and has a breaking strength of 3340 pounds. A minimum 212-to-1 safety load factor, required to allow for overloads caused by excessive ship rolling and pitching, limits the weight of the lowered camera unit to 125 pounds. Loss of this static load from the total wire-weight out, when the sea floor is reached, enables a specially constructed mechanical-electrical dynamometer placed in the fair-lead system of the wire lowering rope to detect small tensional changes in the latter and convert them into electrical signals. Table 1 gives the weight-strength relationships needed to safely lower the camera to a depth of 20,000 feet. Figure 8 illustrates a typical deck arrangement for making a lowering from a vessel. Steady drag forces due to wind and to sea currents, and the dynamic tensional changes in the wire rope caused by roll and pitch of the vessel during inclement weather, are compensated for in the circuitry of the bottom indicator. TABLE 1. Weight-strength relationships for lowering NEL Type Ill Deep-Sea Camera. Wire Wt. in Water (Ib) Wt. Ratio in Water Wire/ Camera Depth (ft) Safety Factor (Wire Rope) 1000 2000 3000 4000 5000 6000 7000 8000 9900 10,000 11,000 12,000 13,000 14,000 15,000 16,000 17,000 18,000 19,000 20,000 8.3 49 Wire rope = 3/16” diam. 3 X 19 preformed galvanized plow steel Nominal breaking strength = 3340 Ib Wt. of wire rope in air = 62 Ib per 1000 linear ft Wt. of wire rope in water = wt. in air less 10% Wt. of NEL Type IIl Deep Sea Camera in air = 215 lb Wt. of NEL Type Ill Deep Sea Camera in water = 125 lb AFTER DECK HYDROGRAPHIC, WINCH 20,000 FT. 3/16" D 3x19 WIRE ROPE WORKING PLATFORM LEVEL WINDER & COUNTER SOFT MAT ON DECK UNDER SHEAVE BN fi SORE ; aN ! 9 \ ooo LB DYNAMOMETER &.2 BOTTOM "ax NDICATOR PADEYE Figure 8. Plan view of a typical deck arrangement for lowering camera and indicating bottom contact. Maintenance and Care of Equipment To reduce the costs of operation, maintenance, and replacement of parts, metals resistant to salt-water corrosion have been utilized as much as possible. Aluminum parts exposed to salt water are anodized and coated with light-weight silicone oil. In fittings where dissimilar metals come into direct contact, frequent rinsings with fresh woter and periodic applications of silicone oil are made. The useful life depends directly upon the attention given to such maintenance. Willard wet cells employed in the illumination unit are given normal battery care and kept in a clean, charged condition. When not in use the cells are removed from the battery compartment of the unit and stored in a charged condition in a safe location where they can be recharged and observed for the need of additional electrolyte. The 22%-volt dry cell in the BC unit which activates the camera shutter solenoid is replaced periodically when in constant use or when its tested voltage drops below normal operat- ing requirements. Silica gel from the compartment located on the base of the camera and power-supply unit is removed and dried periodically to provide maximum protection from moisture resulting from condensation. The 35-mm robot camera when not in use is stored in a moisture-free container to keep it operable. Excessive amounts of moisture or lint in the shutter mechanism will cause malfunction of vital parts. Maximum illumina- tion from the flash tube requires a polished reflector (aluminum, in this case). The clear plastic flash-tube envelope is cleaned carefully to guard against excessive scratching which weakens the plastic and impairs the optical properties. ‘“O’ rings are checked periodically for scratches and flattening and renewed when defects are detected to insure 1] 12 watertight integrity. The clear quartz window in the camera case is examined frequently for flaws and strain cracks caused by excessive applications of high pressure, sharp blows, or improper mounting. It is advisable to allow the camera case to warm up gradually on deck after each deep lowering before opening-up procedures are commenced. This will reduce or eliminate condensation of moisture on camera parts and electrical supplies. Limitations Many factors work singly or together to limit the usefulness or effectiveness of all deep-sea cameras. Weather and sea conditions determine the feasibility of each operation. Underwater conditions such as sea-floor relief, depth, outcrops, rock or sediment type, bottom slope and contact act to limit or increase the number of pictures obtained on each lowering. Vital exposed moving parts of the camera unit, located within the open construction of the frame for protection may suffer occasionally from abrasion and contact with external objects. Deeper lowerings increase the chances for kinks and snarls in the wire lowering rope. Only rapid indication of contact with the bottom will provide the control to keep the wire lowering rope in good condition. APPLICATION OF THE CAMERA TO THE STUDY OF OCEAN-FLOOR ENVIRONMENTS The NEL Type Ill Camera now makes it possible to extend the study of marine environments to depths beyond the limitations of most existing cameras. Deeper bottom features of the continental shelf, continental slope, and abyssal deeps west of San Diego, California, are now being photographed to help reveal the nature of micro-relief on the ocean floor, movement and identification of materials settling to the bottom and the identification and distribution of biological life on, near, and in these modern marine sediments. As the camera continues to be a relatively inexpensive and practical means of investigating the small-scale features of the deep sea floor, improved photo- graphic equipment helps to obtain views which exhibit the greatest amount of natural detail.1°1 Bottom photographs are revealing how burrowing organisms, fish, and other biological life are mixing up and moving bottom sediments; how sediments are being moved along the bottom by currents and down-slope by slumping, sliding, and earth- quake jarrings. Relative grain sizes of bottom materials are revealed. Greater bottom coverage per single lowering of the camera is revealing the distribution of specific bottom materials and biological life. Various forms of biological life living on, near, and in the bottom sediments are being identified from improved underwater photographs (fig. 9). CONCLUSIONS The development of the NEL Type IIl Deep-Sea Camera and its scientific appli- cation to the solution of ocean-floor environmental problems have been justified by the results obtained. The compactness, small size, light weight, and ease of operation and maintenance of the camera permit more extensive field work to be carried on by only a few operating personnel. Relatively small vessels equipped with only 3/16-inch- diameter wire lowering ropes and comparatively light winches are being utilized suc- cessfully for deep-sea photographic operations. Improvements in camera design, equip- ment, and operational techniques are continuously being made to further the needs of oceanographers engaged in the study of sea-floor features. Figure 9. Underwater photographs of some typical sea floor environments taken with the NEL Type III Deep-Sea Camera. Each photograph covers approximately 21 square feet of the bottom at a water distance of 6 ft. Tri-X film with a speed of 200 was used with an 2.8, 3-cm wide-angle lens stopped down to f8. Strobe flash of 1/1500-second light duration provided the illumination. Figure 9A. Brachiopod shells and rounded beach cobbles on a sandy bottom near San Clemente Island, Calif. Lat. 32°-55’ 30”N, Long. 118°-34’35”W. Depth, 396 ft. Note variety of rock fish in upper half of photograph. 13 14 Figure 9B. Holothurian and sea urchins on a pitted, silty bottom, with an eel-like fish above the ocean floor of Loma Sea Valley off San Diego, Calif. Lat. 32°-42’ 30”N, Long. 117°-25' 10”W. Depth, 1656 ft. The tracks and pits in the sediments indicate extensive churning of the bottom materials by burrowing organisms. Figure 9C. Rock outcrop with thin veneer of fine sediments on a bottom slope off the west side of San Clemente Island, Calif. Lat. 32°-50’N, Long. 118°-39’W. Depth, 3234 ft. This is an area of sliding, slumping, and periodic removal of slope sediments into deeper water. Note the deep-sea crab in middle foreground. 15 16 BR % nee S es : ee Figure 9D. Typical red clay bottom at the base of the Continental Slope off the California. Lat. 31°-10’N. Long. 121°-7’W. Depth, 12,780 ft. No biological life is visible coast of Southern in the photograph. The pitted sea-floor surface indicates extensive churning of the sediments by burrowing organisms such as worms. RECOMMENDATIONS 1. Continue investigation of methods of indicating bottom contact. Complete the development of an electro-mechanical device, to be attached to the dynamometer in the lowering equipment, to give good bottom-contact indications for water depths in excess of 12,000 feet. 2. Develop and package a camera with a wide-angle lens and larger film size to be used with a 300 watt/sec flash. 3. Investigate the use of correcting lenses and filters. 4. Investigate the availability, cost, and use of some form of plastic rope of neutral buoyancy for lowering the Type Ill Camera. Such a rope would also help to solve the problem of bottom indication. 5. Develop a direction control for the NEL Type III Camera to extend its use- fulness in the solution of problems dealing with current direction, sources of material supply, and gradients of submarine slopes. REFERENCES Following are the references cited throughout the report, and others suggested as valuable sources of information in the field of underwater photography. 1. Shumway, G., et al. The USNEL Deep Sea Camera (Navy Electronics Laboratory, Report 388) 4 January 1954. 2. Ewing, M., et al. “Photography of the Ocean Bottom” Optical Society of America. Journal vol. 36, no. 6, June 1946, pp. 307-321. 3. Thorndike, E.M. “Color Correcting Lens for Underwater Photography” Optical Society of America. Journal vol. 45, no. 7, July 1955, pp. 584-585. 4. ‘Kodak Lenses,” “Shutters and Portable Lenses” (In: Kodak Data Book) 4th ed., Eastman Kodak Company, 1952. 5. “Kodak Films” (In: Kodak Data Book) 6th ed., Eastman Kodak Company, 1954. 6. Schenck, H. V.N., Jr., and Kendall, H.W. Underwater Photography Cornell Mari- time Press, 1954. 7. “Filters and Polar Screens” (In: Kodak Data Book) Eastman Kodak Company, 1953. 8. Thorndike, E.M. “A Wide-Angle, Underwater Camera Lens’ Optical Society of America. Journal vol. 40, no. 12, December 1950, pp. 823-824. 9. “Flash Technique” (In: Kodak Data Book) Eastman Kodak Company, 1954. 10. Shepard, F. P. and Emery, K. O. “Submarine Photography off the California Coast’’ Journal of Geology vol. 54, no. 5, September 1946, pp. 306-321. 11. Emery, K.O. “Submarine Photography with the Benthograph” Scientific Monthly vol. 75, no. 1, July 1952, pp. 3-11. Cross, E.R. Underwater Photography and Television Exposition Press, 1954. Hahn, J. “Some Aspects of Deep Sea Underwater Photography” Photographic Society of America Section B, June 1950. Harvey, E.N. and Baylor, E.R. “Deep Sea Photography” Journal of Marine Research vol. 7, no. 1, 1948, pp. 10-16. Kingslake, R. Lenses in Photography Case Hoyt Corporation (Garden City Books), 1951. Northrop, J. ““Ocean-Bottom Photographs of the Neritic and Bathyal Environment South of Cape Code, Massachusetts” Geological Society of Ameica. Bulletin vol. 62, no. 12, December 1951, pp. 1381-1384. Owen, D. M. “Deep Sea Underwater Photography and Some Recent Steroscopic Appli- cations” Photogrammetric Engineering vol. 17, no. 1, 1951, pp. 13-19. Vevers, H.G. “Photography of the Sea Floor” Marine Biological Association. Journal vol. 30, no. 1, June 1951, pp. 101-111. Von Bonde, C., ef al. “Preliminary Experiments in Sea Floor Photography in South African Waters” Royal Society of South Africa. Transactions vol. 33, part 1, 1951. 17 a ee i a GaldISSVIDNN Ss! 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Yspy 21U01j29;9 puD ‘wWjy 42}sD} ‘sua) aj]HuD-apiM sj} “42;DM pas ul spunod ¢z, Ajuo syBieMm pup ‘y2oduo> ‘|jDuIs si y1un aut 49294 Q00'0Z JO Yideap D of DIaWDD ayy yO BulJemo| ajBuis D uo paujnjqo aq ups sainjrid woyoq PZ 1sDe] fy ‘sjUaWIpas WOy}Oq 4O Sainyoa} yaljesosIW yO AjAD[NI14 -ind ‘Apnjs 21ydoiBouna20 paaoiduii of pip uD sD peuBbis -8p useq spy tado1 Buiiamo] D yo asn Aq Ajuo payjjosyuo> ‘yun O19WD2 4ayOMJapuN pPeuU!DjuOr-}jas Ajajajdwio> Vy galdISSVIDNN “£561 4Y4PW EL “A ZL yedius “f°D Aq “WYaWVD W45S-d3dG WI AdAL TUN JHL 892 Hodey Asojes0ge] S91N01393)9 Kacy Chief, Bureau of Ships (Code 312) (12 copies) Chief, Bureau of Ordnance (Reé6) (Ad3) (2) Chief, Bureau of Aeronautics (TD-414) Chief of Naval Operations (Op-37) (2) Chief of Naval Research (Code 416) (Code 466) Commander in Chief, U.S. Pacific Fleet Commander in Chief, U.S. Atlantic Fleet Commander Operational Development Force, U.S. Atlantic Fleet Commander, U.S. Naval Air Development Center (Library) Commander, U.S. Naval Air Missile Test Center (Technical Library) Commander, U.S. Naval Air Test Center (NANEP) (2) Commander, U.S. Naval Ordnance Laboratory (Library) (2) Commander, U.S. Naval Ordnance Test Station (Pasadena Annex Library) Commanding Officer and Director, David Taylor Model Basin (Library) (2) Commanding Officer and Director, U.S. Navy Underwater Sound Laboratory (Code 1450) (3) Director, U.S. Naval Engineering Experiment Station (Library) Director, U.S. Naval Research Laboratory (Code 2021) (2) Director, U.S. Navy Underwater Sound Reference Laboratory (Library) Commanding Officer, Office of Naval Research, Pasadena Branch Hydrographer, U.S. Navy Hydrographic Office (1) (Air Weather Service Liaison Office) (1) (Division of Oceanography) (1) Senior Navy Liaison Officer, U.S. Navy Electronics Liaison Office Superintendent, U.S. Naval Postgraduate School (Library) (2) Assistant Secretary of Defense (Research and Development) (Technical Library Branch) NAVY — NEL San Diego, Calif. INITIAL DISTRIBUTION LIST (One copy to each addressee unless otherwise specified) Assistant Chief of Staff, G-2, U.S. Army (Document Library Branch) (3) Chief of Engineers, U.S. Army (Engineer Research and Development Division, Field Engineering Branch) The Quartermaster General, U.S. Army (Research and Development Division, CBR Liaison Officer) Commanding General, Redstone Arsenal (Technical Library) Commanding Officer, Transportation Research and Development Command (TCRAD-TO-1) Chief, Army Field Forces (ATDEV-8) Resident Member, Beach Erosion Board, Corps of Engineers, U.S. Army Commander, Air Defense Command (Office of Operations Analysis, John J. Crowley) Commander, Air University (Air University Library, CR-5028) Commander, Strategic Air Command (Operations Analysis) Commander, Air Force Armament Center (ACGL) Commander, Air Force Cambridge Research Center (CRQST-2) Executive Secretary (John S. 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Emery) Agricultural and Mechanical College of Texas, Head, Department of Oceanography (Dr. D.F. Leipper) The University of Texas Director, Defense Research Laboratory University of Washington, Department of Oceanog- raphy (Dr. R.H. Fleming, Executive Officer) (Fisheries-Oceanography Library) Yale University Director, Bingham Oceanographic Laboratory Director, Lamont Geological Observatory (M. Ewing) The Director, Woods Hole Oceanographic Institution Vitro Corporation of America, Silver Spring Laboratory (Library) VIA BUREAU OF SHIPS: The Admiral, British Joint Services Mission (Navy Staff) (3)