DIFFERENT WINDS AT TORONTO. 11 



The monthly and hourly resultant directions and velocities include 

 only the years 1854 to 1859, and were computed from the well known 

 formulae 



2 2 (v sin 6) — %(v cos 6) 



tan. 6 = ^ , ^= — >^ =r-^- 



2,{vco&6) ncosd 



RESULTANT DIRECTIONS IN THE DIFFERENT MONTHS. 



A comparison of the monthly resultant directions given in table I. 

 shews that the general direction of the atmospheric current is con- 

 siderably more from the westward in the winter than in the summer 

 months, the monthly resultants oscillating about N. 43° W. from April 

 to September inclusive, and about N. 72° "W. during the remaining six 

 months. 



There is a much nearer approach to uniformity of direction in the 

 different years for some months than for others ; for instance, taking 

 the angular difference between a monthly partial resultant in a parti- 

 cular year and the corresponding monthly resultant for the six years as 

 a rough measure of the irregularity of the partial resultant, it is found 

 that the averages of these differences are 7° for January and about 75*^ 

 for June and July. The quarterly averages of the differences are for 

 winter (commencing December 1st), 20° ; for summer, 53° ; for 

 spring, 29° ; and for autumn, 27° : their half-yearly averages being 46° 

 from April to September inclusive, and 19° from October to March. 



RESULTANT VELOCITIES AND MEAN VELOCITIES IN THE DIFFERENT 



MONTHS. 



The resultant velocities and mean velocities have each their maximum 

 in March and their minimum in July. The change from month to 

 month is regular in both, with the exception of a small interruption of 

 continuity in August, and another in December. 



RESULTANT DIRECTIONS OF THE "WIND IN THE DIFFERENT HOURS. 



Confining our attention in the first instance to the annual resultants 

 given in table II., we find that during the hour commencing noon the 

 resultant wind is from N. 103° W., its extreme distance on the left of 

 north. From this point, at which the wind is nearly steady during the 

 three hours commencing at noon, it draws round regularly and continu- 

 ously till it makes its nearest approach to the north (N. 38° "W.) at 5 

 A.M., about which point it remains nearly steady from midnight to 7 

 A.M. It then rapidly recedes again to the westward. 



