[dawsonI effect of WIND ON CURRENTS AND TIDAL STREAMS 183 



speed, by means of a formula determined by experiment; the angle of 

 inclination being measured with a clinometer. 



This simple appliance has proved most serviceable to show the di- 

 rection of the under-current at any depth down to 30 fathoms, which is 

 usually as far as it is necessary to go for the purpose in view. In 

 regions of stronger currents, a weight of modified design is used. It is 

 made of brass tubing, 4 inches outside diameter and 24 inches long, 

 weighted with bars of lead placed inside of it, to a total of 30 pounds. 

 Its use is the same as the fan ; and an equivalent formula for the speed 

 in terms of the angle of inclination has been determined by experi- 

 ment. 



Effect of the wind on the various classes of current. 



The amount of influence which the wind has upon the current de- 

 pends largely upon the strength of the current and its other character- 

 istics. In siimmarizing the extended observations now obtained, it will 

 therefore make the matter clearer to deal separately with the various 

 classes of currents met with. Their general behaviour admits of a classi- 

 fication into four leading types as given below. 



All the directions and bearings are magnetic; the variation in these 

 regions being from 26° to 34° West. 



(1) Weah currents. — The behaviour of the currents off the south 

 coast of Newfoundland affords a good example of this type. In this 

 region, which was examined in 1903, the currents at a distance of five 

 miles from shore, still show a distinct ebb and flow with the tide; but 

 the farther the point of observation is from shore, the less they are under 

 the influence of the tide, and the greater the tendency is to veer com- 

 pletely round the compass. Their strength ati an offing of five miles or 

 more, was never found to exceed one knot per hour in any direction. 



Tlie best observations on the effect of the wind were obtained at a 

 station 17 miles west of Cape St. Mary, in 56 fathoms. Two anchor- 

 ages v/ere made at this station; first for nine days, June 18 to 26, when 

 158 hours of continuous observations were obtained; and again for five 

 days at the beginning of August, when an additional period of 71 hours 

 observation was secured. The usual behaviour of the current was to 

 veer around continuously in a period of 15 to 16 hours. This movement 

 appears to be the resultant of two component elements, one of these 

 being a tidal veer and the other a general westward set along this coast. 

 The strongest winds which occurred were as follows : Wind N", and 

 N. N. E,, with an average velocity of 19 miles an hour for 28 hours; 

 and W. and W. S. W. with an average velocity of 18 miles an hour 

 during 23 hours. These winds did not affect the total period in which 



