been occupied as frequently as practicable to permit accumulation of 

 data for studies of the population and mortality rates of bergs between 

 their source regions in northwestern Greenland and the limits of the area 

 in which they ultimately disintegrate near the steamer lanes in the 

 vicinity of the Grand Banks of Newfoundland. The student of such 

 correlations is warned that the 1948 heat transfer of the West Greenland 

 Current past Cape Farewell must be used with caution since in 1948 

 a considerable heat transfer was associated with the direct contribution 

 to the Labrador Sea of about a million cu. m./sec. from the northern 

 boundary of the North Atlantic eddy. With presently available methods, 

 determination of the mean temperature and heat transfer depend on 

 graphical summation of elemental cross-sectional areas to which are 

 assigned average velocities and temperatures. In dealing with slow 

 water movements the method breaks down as the absolute uncertainty 

 in velocity becomes a large percentage of the computed velocity. Thus 

 it is not feasible to determine the mean temperature and heat transfer 

 of a water movement embodying large cross section and low velocity, 

 such as the inferred direct contribution of the North Atlantic eddy to 

 the Labrador Sea. 



As noted earlier in the discussion in connection with the volume of 

 flow past the triangle north of the Gi'and Banks, both the volume of 

 flow of the Labrador Current of 3.01 million cu. m./sec. past the South 

 Wolf Island section and its mean temperature of 2.21° C. were lower than 

 the average values for earlier occupations of the South Wolf Island 

 section from 1928 to 1941. This is probably associated with the de- 

 creased activity and lowei" mean temperature of the West Greenland 

 Current which supplies the warmer offshore component of the Lab- 

 rador Current. 



In balancing volumes of flow it has l)een indicated in figure 36 that 

 of the Labrador Current passing the South Wolf Island section about 

 one third of a million cu. m./scc. recurves northward in the closed cir- 

 culation of the Labrador Sea, leaving about 2/^ million to continue south- 

 ward to the triangle north of the G)-and Banks. As about 3H million 

 was the volume of flow found for the northern section of the triangle 

 it is assumed that the offshore corner of the triangle extended into a 

 counterclockwise eddy which contributed about two thirds of a million 

 cu. m./sec. to the circulation past the triangle. 



During the 1948 season and post-season cruises field tests were made 

 of a new instrument which holds great promise of utihty to the Inter- 

 national Ice Patrol. Since the days of Faraday it has been known that 

 water in motion (such as an ocean current) relative to a magnetic field 

 (such as the earth's magnetic field) would result in the generation of an 

 electromotive force just as any other conductor cutting flux. It re- 

 mained for William S. von Arx of the Woods Hole Oceanographic Insti- 

 tution to translate this principle into a practical instrument for measuring 

 ocean currents from a moving ship. The instrument, which he has named 



92 



