THE SMITHSONIAN INSTITUTION. 223 



TABLE XVIII. 



MEAN DIURNAL VARIATION OF THE FORCE OF WIND, IN POUNDS, AT PHILADELPHIA. 



Computed from the observations made in 1843 and 1844. 



Maximum. 



Minimum . 



Table XVIIT, compared with table IX, exhibits a greater mean pres- 

 sure of the wind at Greenwich than at Philadelphia. The maximum 

 intensity, during the whole 24 hours is, in both tables, at 2 p.m. 



TABLE XIX. 



mean DIURNAL VARIATION OF THE SKY COVERED BY CLOUDS, AT PHILADELPHIA. 



Computed from the observations made from the 1st July, 1843, to 1st July, 1845. 



Minimum. 



Maximum. 



Tables XIX and VI exhibit nearly the sam.e variation in the lime 

 of greatest and least cloudiness at Greenwich and Philadelphia. 



