Meteorological Observations at Hudson, Ohio. 323 



The force of the wind is least at 4 A. M. and greatest at 1 

 P. M. ; the latter being 2.63 times the former. The curve 

 representing these observations is found to be ahnost identical 

 with that of the thermometer, not only for the whole year but 

 for each season. This result develops a most important prin- 

 ciple, and demonstrates the error of those who ascribe to heat 

 an unimportant influence in the production and modification of 

 winds. It is here demonstrated by direct observation, that at 

 certain localities, and there is good reason to believe that in this 

 respect they are not peculiar, the wind is subject to a controlling 

 influence, ichich has a period of twenty four hours; an influence 

 not feeble or of doubtful existence ; but powerful, at one hour 

 retarding it by nearly one half its mean velocity, and at another 

 accelerating it by the same quantity ; changing not merely its in- 

 tensity but its direction, for from the table on page 320, it will 

 be seen that the wind is more northerly at 3 P. M. than at 9 A. M. 

 for every month of the year. Taking these facts in connection 

 with the well known eflects of heat, we are warranted in the 

 conclusion that the heating power of the sun's rays is to be re- 

 garded as the physical cause of this diurnal change in the direc- 

 tion and intensity of the wind. 



CLOUDS. 



The following table exhibits the progress of the clouds, each 

 observation being resolved in the direction of the cardinal points 

 in the same manner as for the winds. The table contains the 

 sum of the observations for three years. 



It appears then that the mean direction of the clouds for each 

 month is very nearly from the west, fifteen degrees being tlie 

 greatest deviation. The clouds are all of necessity supposed to 



