[dawson] effect of WIND ON CURRENTS AND TIDAL STREAMS 191 



and amounting to a total of 3,155 miles in 81 hours, up to 21 o'clock on 

 the 3rd. At Belle Isle, the wind was steadily W., and averaged 413 miles 

 per day. On anchoring in the strait on July 4, the surface current in 

 the ebb direction ran for 20 minutes longer than the under-current at 25 

 fathoms; and on the following morning, in the flood direction for 15 

 minutes longer. These amounts are quite within the usual limits; and 

 cannot be taken to indicate any disturbance of the surface relatively to 

 the under-current. 



On August 17 a northeast gale occurred. From 8 o'clock on the 

 16th to 7 o'clock on the 18th, the wind held steadily in the X.E., 

 amounting to a total of 1,550 miles in this period of 47 hours. The 

 eteamei^ was in Red bay on the 17th, where the full force of the wind 

 was not obtained. At Belle Isle, the wind ranged from N.E. to N. 

 Current obsej'vations were obtained immediately afterwards, from the 

 morning of the 18th, in the middle of the strait. At the first high-water 

 slack the current in veering from west to east did not pass the north 

 point till 1 h. 05 m. after the turn of the under-current; and at low- 

 water slack it passed the south point 20 m. before the turn of the under- 

 current. This modification of the veer and the consequent shortening 

 of the ebb period relatively to the under-current, were the only indica- 

 tions of disturbance which the current showed. 



On the night of September 11-12 there was heavy west wind, rising 

 to 43 miles an hour. During 24 hours up to 18 o'clock on the 12th, 

 there were 546 miles of wind between W. and S.S.W. The night of 

 September 12-13 was calm. On anchoring in tlie strait, the low-water 

 slack at mid-day on the 13th turned simultaneously on the surface and 

 in the under-current, showing no appreciable disturbance. 



The heaviest gale of the season occurred on the night of September 

 14-15, when the velocity in Red bay reached 68 miles an hour. For 

 three days the wind conditions were as follows : On the 14th from 20 to 

 24 o'clock, W. 107 miles; on the 15th throughout the 24 hours, N. 692 

 miles; during the 16th and up to 6 o'clock on the 17th, î^[., N. W. and 

 W., 224 miles. Total mileage during 58 hours, between north and west, 

 1,023 miles. 



For a week before and after this time, the dominant flow was so 

 largely westward that the current seldom turned. Accordingly, on the 

 17th the current, as observed in the day time, set continuously south- 

 westward; and throughout the ebl) period the surface direction was be- 

 tween southwest and south, while the under-current set eastward for 3I/2 

 hours. The corresponding ebb on the following day set weakly eastward 

 on the surface as well as below. Hence the direct influence of this gale 

 was not sufficient to overcome the dominant flow and set the surface 



