BALL BREAKER . Coring and sampling activities in 

 deep-sea areas present the problem of determining 

 the moment of contact of the instrument with the 

 bottom in order that the winch may be stopped im- 

 mediately. When sampling in deep water the weight 

 of the coring device is often a small part of the 

 total weight of the wire out and of the variable 

 loads caused by the ship's rolling. Thus, no ap- 

 parent drop in tension may be observed on the dyna- 

 mometer when the bottom is reached. One device 

 used to indicate contact between corer and bottom 

 is the ball breaker. A hollow glass ball, 3 to 5 

 inches in diameter, is lightly held in a frame at- 

 tached to the trigger line above the triggering 

 weight of the corer. Above the ball is a weight 

 with a sharp protrusion pointing downward. Vfhen 

 the corer strikes the bottom the line becomes slack 

 releasing the weight which strikes the ball. The 

 resulting implosion may be heard on some types of 

 echo sounders or received on a Brush recorder wired 

 to the echo sounder. (35) 



LOWERING 



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BALL ICE . Numerous floating spheres of SEA ICE 

 having diameters of one to two inches. The balls 

 are very soft and spongy; no internal structure 

 can be distinguished clearly. The balls are 

 generally in belts similar to SLUSH which forms at 

 the same time. Ball Ice has very rarely been 

 reported. (25) 



BALNIRO . The Baltic Research Institute of Marine 

 Fisheries and Oceanography (USSR) . 



BAND ELIMINATION FILTER . 



is a wave filter that has 



for one frequency band, with the cutoff frequencies 



for this band neither zero nor infinite. (8) 



A band elimination filter 

 a large insertion loss 



BAND LEVEL . A given spectrum level is usually 

 associated with a specific frequency. To identify 

 a transmission level measuring the power in a speci- 

 fied frequency band, or the acoustic intensity in a 

 specified frequency band, it may be designated as a 

 band level. (4) 



BAND-PASS FILTER . A band-pass filter is a wave 

 filter that has a single transmission band extend- 

 ing from a lower cutoff frequency greater than 

 zero to a finite upper cutoff frequency. (9) 



BAND PRESSURE. LEVEL . The band pressure level of a 

 sound for a specified frequency band is the sound 

 pressure level for the sound contained within the 

 restricted band. The reference pressure must be 

 specified. (2) 



BAND RATIO . In many problems the ratio, f^/fa" 

 between the limiting frequencies of a given band is 

 of more significance than their difference. This 

 ratio, which may be spoken of as the band ratio, is 



represented graphically by an interval on a loga- 

 rithmic scale of frequency. (4) 



BAND WIDTH . When frequency is plotted against a 

 linear scale any interval along that scale measures 

 the difference, fj, - fg, between the frequency of 

 the upper boundary of the band represented and the 

 frequency of the lower boundary. This difference 

 is known as the band width of the frequency band. 

 Bands having equal widths are represented on a 

 linear frequency scale by intervals of equal 

 length. (4) 



BANK . (1) The rising ground bordering a lake, 

 river, or sea. On a river designated as right or 

 left as it would appear facing downstream. (2) 

 An elevation of the sea floor of large area, sur- 

 rounded by deeper water, but safe for surface 

 navigation; a submerged plateau or shelf, a shoal, 

 or shallow. (10) 



BANNER CLOUD . A banner like cloud streaming off 

 from a mountain peak in a strong wind. (17) 



BAR . 1. An offshore ridge or mound of sand, 

 gravel, or other unconsolidated material submerged 

 at least at high tide, especially at the mouth of a 

 river or estuary, or lying a short distance from 

 and usually parallel to, the beach. (11) 



2. A unit of pressure equal to 1,000,000 

 dynes per square centimeter, 1,000 millibars, 29.53 

 inches of mercury. (24) 



BARALYME . A compressed pill consisting of a blended 

 mixture of barium octohydrate and calcium hydroxide. 

 It is used as a carbon dioxide absorbent in re- 

 breathing (diving) systems. 



BARAT. A heavy northwest squall in Menado Bay on 

 the north coast of the island of Celebes, prevalent 

 from December to February. (17) 



BAR . BAYMOUTH . A bar extending partially or entire- 

 ly across the mouth of a bay. (11) 



BARBER . 1. A severe storm at sea during which 

 spray and precipitation freeze onto the decks and 

 rigging of boats . 



2. (Also spelled berber.) In the Gulf 

 of St. Lawrence, a local form of blizzard in which 

 the wind-borne ice particles almost cut the skin 

 from the face. (24) 



BAR BUOY . A buoy marking the location of a bar. 

 (17) 



BAR, CUB PATE . A crescent shaped bar united with 

 the shore at each end. It may be formed by a 

 single spit growing from shore turning back to 

 again meet the shore, or by two spits growing 

 from shore united to form a bar of sharply cuspate 

 form. (10) 



BARNACLES . Marine crustaceans, most of which 

 attach and grow on hard objects at or below the 

 surface and have a calcareous shell. Some are 

 called Sea Acorns. (15) 



BAROCLINITY . The state of stratification in a 

 fluid in which surfaces of constant pressure 

 (isobaric) intersect surfaces of constant density 

 (isosteric). The number, per unit area, of iso- 

 baric-isosteric SOLENOIDS intersecting a given sur- 

 face is a measure of the baroclinity. If the sur- 

 face is horizontal, this number N is given by 



9p Ba 

 9x 3y 9x 9y 



where a is the specific volume and p the pressure. 

 (24) 



BAROMIL . The unit length used in graduating a mer- 

 cury barometer in the centimeter-gram-second system. 



(continued on next page) 



N = ^ 1p 



11 



