9 



region, covered by the map, that it is necessary to search is thus 

 limited and scouting unnecessary areas is avoided. The use of the 

 charts in this way is valuable, especially in the late spring, when 

 the currents cannot be detected by surface-temperature records be- 



52° 51° 50° 



Figure 2. A composite chart to illustrate the Qlose correspondence of the actual drift of 

 bergs with the lines of flow as shown on the dynamic current charts. Above and to the 

 left of the heavy black line is shown the drift of a berg from 18 to 23 June 1935, plotted 

 against the streamlines of the current map completed 10 June, indicated by the arrows 

 (see fig. 21). Below and to the right is shown the drift of a berg from 15 to 25 May 

 1935, plotted against the streamlines of the current map completed 18 May, indicated 

 by arrows (see fig. 20). In both cases, the dotted line between the berg's successive 

 positions shows the drift as observed by the patrol vessel. 



cause of excessive solar warming at the surface which masks the 

 cold, deeper circulation. The success of the Patrol, using the maps 

 in these two ways, which adds materially to the effectiveness of the 

 service, justifies their continued construction. A detailed descrip- 

 tion of the operations of the oceanographic vessel will be found 

 elsewhere in this volmne under Oceanography (p. 83). 



