76 



RECORD AND DISCUSSION OP FORCE OP WIND. 



Resulting Monthly Direction of the Wind. The resulting monthly direction &amp;lt;|&amp;gt; of the 

 wind is obtained by adding up the velocity-numbers for each wind separately, from 

 the hourly observations taken during the month, irrespective of omissions. The 

 numbers thus obtained are then treated in accordance with the preceding formula;. 

 For the month of September, 1853, for instance, we would have 



Hence c = + 839 



d = + 417 



c d = + 422 



c + d = +1256 



0.7 (&amp;lt;: d) = + 295 



0.7 (c + &amp;lt;/) = + 879 



a =_ 306 



C = + 110 



E 8 == 11 



R w = +995 

 li = 995 



&amp;lt;!&amp;gt; =89 22 



equivalent to a 



west wind. 



To convert the resulting &amp;lt;p from the magnetic into the true direction, apply the 

 magnetic declination, viz: 108 12 west. 1 



In like manner, the mean direction of the wind for each month has been made 

 out. The following table exhibits the sum of the velocity-numbers for each wind, 

 as well as the resulting direction of the winds for each month of observation : 



To obtain the resulting direction of the wind in each month, each season, and for 

 the whole year, we first take the mean of the values R s and R w respectively, for 

 the same months in the different years and find 



1 See my discussion of Dr. Kane s niagnetical observations, in Vol. X. of Hie Smithsonian Contribu 

 tions to Knowledge, 1858, p. 25. 



