6 MARIOX AND GENERAL GREENE EXPEDITIONS 



bottom water. Helland-Hansen believes Arctic contributions are 

 indicated in what few observations there are recorded from the deeper 

 parts of the northwestern North Athuitic. 



In 1913 the Grand Banks and Atlantic waters adjacent to New- 

 foundland received their first systematic study. Dr. D. J. Matthe\ys 

 (1914), on the steamship Scotia, carried out these investigations in 

 connection with a service providing better protection for trans-At- 

 lantic steamers against the menace of x\rctic ice. Some of the main 

 results of Matthew's sunmiary are {a) the Labrador Current has 

 salinities on the surface between 82.5 and 33.5%o which increase 

 with depth, while a temperature minimum as low as —1.8° C, is to 

 be found at depths of 50-75 meters; (6) the Labrador Current splits 

 into three parts on the northern edge of the Grand Banks; (1) the 

 westerly branch flows around Cape Race; (2) the middle and most 

 important arm follows the eastern edge of the Grand Banks, prob- 

 ably diving under the Gulf Stream; and (3) the eastern arm flows 

 eastward to the north of Flemish Cap; (c) the Grand Banks is 

 dominated by no single definite current, the general tendency of 

 the circulation appearing to be that of a great eddy with a slow 

 southeastward drift; and finally {d) the velocities of the Labrador 

 Ciu'rent are as a rule relatively weak. 



April 14, 1914, the United States Coast Guard in conjunction 

 with its International Ice Observation and Ice Patrol service, inau- 

 gurated subsurface observations of temperature and salinity in 

 the Grand Banks sector. The program except for the World War 

 years, 1917 and 1918, has been continuous and gradually amplified. 



The observations prior to 1922 were taken at unrelated positions 

 and often separated by considerable intervals of time. During the 

 ice season of 1922, and subsequently, the stations for observations 

 have been located, for the most part, along lines normal to the 

 Grand Banks slopes and as synoptic as the duties of the ice patrol 

 ship permitted. The current maps constructed by means of these 

 observations were found to be of such practical value both in fol- 

 lowing the movement of the icebei-gs and in providing a higher 

 degree of protection for the transatlantic steamships (see Smith 

 1931, p. 175) that in 1931 the ice patrol cutter was relieved of the 

 task of collecting subsurface observations by the addition of a third 

 vessel to the service. LTnder the ])resent program the oceanogi-aphic 

 vessel occupies between 100 and 200 stations for observations during 

 the normal ice season which constitute the data for three or four 

 maps of the circulation around the Grand Banks. The selection 

 of the particular sea area surveyed depends mostly upon the dis- 

 tribution of the icebergs at the time, but it usually embraces the 

 slope waters and ranges in latitude from the vicinity of Flemish 

 Cap to the Tail of the Grand Banks or even as far south as the 

 fortieth parallel. The size of the area mapped and the extent of 

 the deepest observation depends upon the urgency of the informa- 

 tion ; prior to 1931 the oceanogra})hic work was nmch curtailed below 

 what it is now on account of the necessary scouting duties of the 

 ice patrol cutter itself. Since the assignment of an oceanographic 

 vessel observations have been made to 1,000 meters depth and every 

 second or third station in tlie deeper water is extended to 1,500 

 meters. 



