OF THE DIRECTION AND FORCE OF TIIE WIND. 



67 



Tims, for September, 1857, we found R = 137, and n = number of observations 

 (minus calms) = 170, bence V= 0.8. The following table contains the quantities 

 for eacb month, season, and the whole year. The numbers for April, 1858, were 

 changed so as to refer to 12 daily observations throughout. A similar remark 

 applies to March, 1S59, and to July, 1859. 



At Van Rensselaer, the annual mean was V = 4.5. 



Average Velocity of the Winds. — The average velocity with which each of the 

 eight principal winds passes over the place of observation in each month, season, 

 and whole year, is found by dividing the sum of the velocity-numbers of each wind 

 by the number of entries in the period; thus, for the month of September, 1857, 

 we have — 



True direction of the wind. 

 S. 



s. w. 

 w. 



N. W. 



N. 



N. E. 

 E. 

 S. E. 



Sum 



2082 



no 



12.3 



The following table shows the mean velocity of the winds, expressed in miles 

 per hour, for each month of observation : — 



