501 



The smoothed curve for the summer four months shows a decrease of force from the maximum at 4 p.m. 

 to a well-marked minimum between G a.m. and 7 a.m. ; from 7 a.m. to noon it increases again steadily, 

 but a slight inflexion is then shown in the curve to a small secondary minimum at 2 p.m., before the 



012345678 9 10 ii N. 12345 67 



10 



9 



8 



7 



6 



17 



16 



13 

 12 



13 



a 12 

 k ii 



10 



.3 ii 

 I 



Autumn 



Spring 



Spring / 



Apr. 



Sep.- Oct. 



ir. Apr. '03. 



\ 



902^-1905 combined 



Autumn combined 



\ 



\ 



\ 



Fig. 6. Diurnal variation of \viml velnuily. 



maximum of the day is reached at 4 p.m. The smoothed curve approximates very closely to the summer 

 curve for 1902-3, but is more divergent from that for 1903-4; in both years, however, confirmation is 

 given, although in varying degrees, to the secondary minimum early in the afternoon. With the 

 exception of this minimum the summer curve of wind force coincides fairly well with the diurnal march 



