77 



that the currents continued to maintain the previously described 

 set around the Tail and on to the southwest slope. 



The period of fog mentioned in the preceding paragraph might 

 suggest the following questions to one not thoroughly acquainted 

 mth the ice patrol work: "How complete is the ice report broad- 

 cast by the patrol ship?" ''Can steamships approaching the ice 

 regions rely confidently on the patrol's report as being final ?" "Does 

 the ice patrol know the location of all of the icebergs in the North 

 Atlantic?" The essence of the idea which suggested a patrol of the 

 ice regions is based upon the theor}^ that a ship could maintain con- 

 tinuous contact with the western, southern, and eastern iceberg 

 limits during the ice season. It is believed that, with few exceptions, 

 caused by unusually protracted periods of fog, the patrol, as at 

 present organized, is cognizant of all ice that drifts south of the Tail 

 of the Grand Bank. In other words, it is rare for the passing steamer 

 to report a berg south of the 43d parallel the presence of which is not 

 known to the ice patrol. A year in which there is an abnormal 

 number of bergs may require modification of this statement. It is 

 the policy of the patrol, however, to keep informed regarding the 

 position of all bergs in the North Atlantic south of the 43d parallel. 

 In order to accomplish this, diligent search of this area is made at 

 frequent intervals, except when handicapped by fogs. North of the 

 43d parallel the patrol is forced to rely upon the reports of passing 

 ships, except when able to make an occasional excursion into that 

 region. All reports received are compiled and a daily broadcast 

 made up for the area northward to the 48th parallel. 



The boundary between the warm and the cold water during the 

 first part of April followed an undulating line between the 42d and 43d 

 parallels south of the Grand Banks. The last half of the month its 

 contour assumed a less swirling form 20 miles southward in lat. 41° 

 20', long. 50° 00'. It also assumed a wedge-shaped form which, 

 extended southeastward to lat. 41° 00', long. 47° 30' (see charts "H" 

 and "I"), corresponding to the bathymetrical contour of the Grand 

 Banks in its deeper soundings (see chart "E"). Such wedge-shaped 

 form for the cold water was observed by the patrol in 1921 and 1922 

 (Treasury Department Bulletins Nos. 9 and 10, "International Ice 

 Observation and Ice Patrol Service"), and also is mentioned by 

 Helland-Hansen and Nansen: "Temperature Variations in the North 

 Atlantic Ocean and in the Atmosphere." Smithsonian Miscellaneous 

 Collections, vol. 70, No. 4, 1920. 



The head of warm water usually encountered in long. 53° 00', 

 west of the Tail of the Bank, was not as prominent as usual this 

 year, and the southerly position of the "cold wall" during the latter 

 half of the month indicated an influx of cold water around the Tail. 



88124—24 6 



