IO.S SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 51 



But this value has neither practical nor scientific interest because 

 it corresponds to the whole scale of different velocities of the wind 

 from 5 meters per second up to 20. This itself explains the impor- 

 tance of the so-called mean error. 



By grouping the numbers in such a way that each group corre- 

 sponds to a certain velocity we have formed the following table: 



The negative values show the cases where the wind deviated to 

 the left, in spite of the theory, and not to the right of the rectilinear 

 direction. 



After having submitted this table to a detailed examination, 

 which I need not repeat here, we have obtained the following values 

 of t he coefficient jj. corresponding to four different values of v. 



15.9 0.092 



Representing these figures graphically by orthogonal coordinates 

 we obtain a very regular curve, a sort of parabola, whose natural 

 prolongation crosses the axis of ft at some distance from the origin. 

 The equation of such a parabola, as we well know, is 



fi = c v 2 +c' (5) 



where c and c' are constant parameters. The introduction of 

 the parameter c' is explained by the law of Dove, according to 

 which the weather vane at any meteorological station in Europe 





