134 MAEION EXPEDITION TO DAVIS STRAIT AND BAFFIN BAY 



miles per day with a wind force of 4 to 5. There is, however, one 

 modifyintr factor, namely, the deep draft of the ice, 500 to 600 feet, 

 which exceeds the depth of the wind current. The bottom portion of 

 the body dra<r<iin<>- in the deep, dead water Avill. therefore, retard 

 the ice probably as much as 20 per cent. In the case of the bulky 

 and boxlike type of ber<r it will reduce the drift to 2 and 3 miles 

 per day for 4 to 5 and to T winds, respectively, but the smaller- 

 wini^ed and pinnacled berijs float entirely in the Avind current and 

 develop no dra^ whatsoever. 



Now, coml)inin<r (a) and (b) (p. 188). we arrive at a resultant 

 drift Avhich for the deeper-draft type of ber<>s is 40° to the right of 



Wind Effect on the Drift of Large icebergs 



Figure 88. — In the case of a wind with a velocity of 4-5 

 Beaufort scale, the berg will ilrift 40° to the i-ight of 

 the wind (in the Northern Hemisphere), at the rate of 

 I'.S miles per day ; line A in this tigure. In the case of 

 a wind velocity of 6-7 Beaufort scale, the berg will drift 

 40° to the right of the wind at the rate 'of 4.o miles per 

 day : line B. 



the wind. Column A represents the drift that the wind would im- 

 part to the ber<r if it did not affect the water and column B represents 

 the mean f rictional current for winds of tiie given streniith. We have : 



1 Miles per day. 



In the case of the lighter draft bergs, i. e., those of proportions 2 : 1 

 and 1 : 1, drift 54° to the right of the wind as follows : 



Miles per day. 



