88 



bergs. Charts '' F " and " G " show that the drift tracks of the 9 bergs 

 (J, D, E, M, N, L, R, S, and P) were similar, yet occurring at different 

 times during a period covering 2 months and 12 days. In May 

 the winds were from the west and northwest, the average strength 

 being 4 and 5. During the first half of June the winds became 

 southerly and their average intensity was not over 4, while during 

 the second half of June light breezes, equally divided between the 

 SE. and SW. quadrants, witli an average strength of 2^, prevailed. 



July 1 to 15 the wind was confined almost entirely to the SW. 

 quadrant, its average force being 4. It will be seen from this that 

 the winds ^ did not remain the same in direction and force during 

 this period, yet the bergs (see charts "F" and ''G'') followed approxi- 

 mately similar drift tracks. 



May 2 to 13. 1922, bergs "D" and "E" « drifted westward from 

 the Tail of the Bank, a distance of 90 miles, although the wind dur- 

 ing this time was constantly blowing from the west against the bergs. 

 One of the days, May 4, it blew west-northwest, force 6. yet the 

 bergs "D" and "E" continued to drift into the face of the wind at 

 the rate of 0.3 knot per hour. 



The direction and force of the wind for 1923 is indicated on charts 

 "B" and'C." 



Since 1921 the patrol has observed only one case in which the wind 

 appeared to influence the drift of a berg. 



It is generally conceded that the frictional effect of wind sets up 

 currents in the upper layers of the ocean, the magnitude of the 

 current set up, i. e., the velocity and volume of the water mass 

 set in motion, being directly proportional to the strength and dura- 

 tion of the wind, though not necessarily in the same direction. The 

 phase of the subject most immediately bearing on the drift of ice- 

 bergs is, to what depth does the wind impart motion to the water 

 particles in the ocean? Some information is obtainable from the 

 subsurface sections taken at right angles to the cold wall during June 

 and July, when the prevailing southerly winds tend to blow a surface 

 layer of warm tropical water over the colder mixed water to the 

 northward. 



The average height of a berg south of the 45th parallel is 75 to 100 

 feet. wSuch a berg would possess a mean draft of 300 to 400 feet or 

 more. It can be seen from this that the drift of bergs is necessarily 

 controlled by relatively deep-seated, major circulatory movements 



' 1901. Dlokson, N. H.; "The Circulation of the Surface Waters of the North Atlantic," Phil. Trans. 

 Roy. Soc. London. Scr. A. Vol. 19C. 



1020. Hellitntt-UHnsen & Nanscn; "Temperature Variations in tlu' No. Atlantic and in the Atmos- 

 phere." Smithsonian Miscellaneous Collections, vol. 70. No. 4. 



lOLS. .Sandstrom, J. W.; "Canadian Fisheries Expedition lOU-lT)," Bull. Dept. Marine and Fisli- 

 eries, Ottawa. 



' 1022. Treasury Department Hullotln No. 10, chart "F." 



