States waters, a bell buoy Is a flat-topped float 

 with a skeleton superstructure supporting the bell. 

 (17) 



BENCH . 1. A level or gently sloping erosion plane 

 inc lined s eawar d . 



2. A nearly horizontal area at about the 

 level of maximum high water or the sea side of a 

 DIKE. (11) 



BENCHMARKS (B.M.) . A fixed point used as a refer- 

 ence for elevation. (11) 



BENDING . The first stage in the formation of 

 PRESSURE ICE caused by the action of current, wind, 

 tide, or air temperature changes. Bending is more 

 characteristic of thin, plastic ice than heavier 

 forms. (25) 



BENDS. See DECOMPRESSION SICKNESS. 



BENGITELA CURRENT . The northward flowing current 

 along the west coast of Africa; it is one of the 

 swiftest of ocean currents, the strongest current 

 in the South Atlantic. It is a continuation of 

 the SOUTH ATLANTIC CURRENT. Proceeding toward the 

 equator, the Benguela current gradually leaves the 

 coast and continues as the northern portion of the 

 SOUTH EQUATORIAL CURRENT. (24) 



B ENTHIC DIVISION . A primary division of the sea 

 which includes all of the ocean floor. The Ben- 

 thic Division is subdivided into the LITTORAL 

 SYSTEM (the ocean floor lying in water depths 

 ranging from the high water mark to 200 meters 

 or the edge of the continental shelf), and the 

 DEEP-SEA SYSTEM (ocean floor lying in water 

 deeper than 200 meters). The systems are further 

 subdivided into the EULITTORAL ZONE (0-50 meters), 

 SUBLITTORAL ZONE (50-200 meters), ARCHIBENTHIC 

 ZONE (200-1000 meters), and the ABYSSAL-BENTHIC 

 ZONE (1000 meters and greater) . (13) 



BENTHITHERMOPROBE . This instrument was constructed 

 when it was discovered that the bottom of some 

 shallow bodies of water is significantly warmer 

 than the water immediately above the bottom. The 

 probe is a positive means of placing the sensing 

 element directly on the bottom and positioning it 

 accurately. In a soft bottom it can be forced 

 down in the sediment a short distance to examine 

 temperature gradients in the upper half meter or 

 so. A brass friction fitting at the sensing element 

 end of the probe, resembling the web-ring at the 

 lower end of a ski pole, is moved upward along the 

 probe by the surface of the sediment as the probe 

 is forced into the mud. The maximum extent of 

 penetration into the sediment can thus be deter- 

 mined. The instrument consists of a pair of 

 matched thermistors potted in the end of a slender 

 aluminum tube. It is connected to an indicator 

 case containing the bridge circuit by a two conduc- 

 tor cable. (30) 



BENTHOS . The category of marine organisms that live 

 on, in, or close to the bottom of the oceans. (27) 



BENTHOS V. A manned submersible vehicle (US). 



high. On mean charts of sea-level pressure, this 

 high is a principal center of action. 



Warm and humid conditions prevail over the 

 eastern United States, particularly in summer, when 

 the Bermuda high is well-developed and extends west- 

 ward . (24) 



BERTH . A place for securing a vessel. (17) 



BESET . Surrounded so closely by sea ice that steer- 

 ing control is lost. The term does not imply pres- 

 sure. If the vessel is incapable of proceeding, it 

 is icebound. If pressure is involved, the vessel 

 is said to be nipped. (17) 



BIDIRECTIONAL HYDROPHONE . A bidirectional hydro- 

 phone is a HYDROPHONE whose response is a maximum 

 for sound incident at two directions 180° apart. 

 (1) 



BIDIRECTIONAL TRANSDUCER . A transducer having 

 maximum response in both directions along a refer- 

 ence axis passing through its center is said to be 

 bidirectional. (4) 



BIFILAR CURRENT INDICATOR . An apparatus formerly 

 used for obtaining the direction of the current at 

 different depths. It consisted of several sets of 

 vanes and indicators mounted on a shaft to obtain 

 simultaneously the direction of the current at dif- 

 ferent depths. Each vane was attached by two wires 

 to an indicator which moved over a PELORUS . (14) 



BIFURCATION BUOY . A buoy marking the point at 

 which a channel divides into two branches when pro- 

 ceeding from seaward. The opposite is JUNCTION 

 BUOY. See MIDDLE GROUND BUOY. (17) 



BIGHT . A slight indentation in the shore line of 

 an open coast or of a bay, usually crescent shaped. 

 (10) 



BILATERAL SYMMETRY . Symmetry such that a body or 

 part can be divided by one median plane into equi- 

 valent right and left halves, each a mirror image 

 of the other. (19) 



BILATERAL TRANSDUCER . A bilateral transducer is a 

 transducer capable of transmission in either 

 direction between its terminations. (1) 



BINARY FISSION . A reproductive process in which an 

 individual organism divides into two halves, often 

 equal, after which each grows to the original form. 

 (19) 



BINARY NOTATION . A system of positional notation 

 in which the digits are coefficients of powers of 

 the base 2 in the same way as the digits in the 

 conventional decimal system are coefficients of 

 powers of the base 10. (31) 



Binary notation employs only two digits, 1 and 

 0, therefore is used extensively in computers where 

 the 'on' and 'off positions of a switch or storage 

 device can represent the two digits. 



In decimal notation 111 = (1 x 10"^) + (1 x lO-*") 

 + (1 X 10°) = 100 +10 1 = one hundred and eleven. 



In binary notation 111 = (1 x 1^ + (1 x 2^) 

 + (1x2°) ■= 4 + 2 + 1 = seven. 



BERGY BIT . Name applied to a small iceberg about 

 the size of a house. (12) 



BERM CREST ( BERM EDGE) . The seaward limit of a 

 BERM. (11) 



BERM EDGE . See BERM CREST. 



BERMUDA HIGH . The semi-permanent SUBTROPICAL HIGH 

 of the North Atlantic Ocean, so named especially 

 when it is located in the western part of the ocean. 



This same high, when displaced toward the 

 eastern part of the Atlantic, is known as the Azores 



BINNACLE . The stand in which a compass is mounted. 

 For a magnetic compass it is usually provided with 

 means of mounting various correctors for adjustment 

 and compensation of the compass. (17) 



BIOCHORE . See BIOTOPE. 



BIOCOENOSIS . See BIOTOPE. 



BIOGENOUS DEPOSITS . Deposits having more than 30 

 per cent material derived from organisms. (27) 



BIOLOGY (MARINE) . The study of the life history 



14 



