NO. 17.] 



WIND. 



291 



The horizontal row "Mean" in the Table contains the direct means for 

 the three or two years of observation. The horizontal row "Sm." gives a 

 smoothed series of numbers, computed from the formula 



W a 



cp e 



P a 



b h being the smoothed value for the respective hour, 6 the value in the 

 column "Mean", a and c the values for the adjacent hours of observation, 

 p a , pi, and PC the respective weights, taken proportional to the numbers of 

 observations. 



The Table shows that there is in each month a remarkably well-defined 

 diurnal period in the velocity of the wind. From the table. and diagrams, I 



