Atmospheeic Peessuee. 



419 



Diurnal Ranges of the Hourly Variations of Humidity for each Month. — The ranges for each month from 

 Table XVI. are— 



Jan. 



0-081 



Feb. 



0-138 



March. 



0-186 



April. 



0-266 



May. 

 0-285 



June. 



0-216 



July. 



0-251 



Aug. 

 0-258 



Sept. 



0-228 



Oct. 



0-170 



Nov. 



0-080 



Dec. 



0-051 



The diurnal range is least in December and is gi-eatest in April and August. The mean range of the diurnal 

 variation of humidity is less for the midsummer months, June and July, than for the two preceding or two suc- 

 ceeding months. 



TAe Extremes of Daily Mean Humidity and their Ranges are as follow for each month of 1844 : — 



July. Aug. Sept. Oct. Nov. Dee. 



0-937 0-920 0-967 0-941 0-974 0995 

 0-716 0-724 0-743 0-758 0-719 0-822 



Ranges, 0-230 0-204 0-196 0-313 0-293 0-228 0-221 0-196 0-224 0-183 0-255 0-173 



The greatest daily mean of relative humidity occurred on the 19th December when the air was nearly satu- 

 rated, and the least occiu-red on the 30th April when the air contained only -J''^ of its capacity. The greatest 

 range of diurnal means for a month, is that for April, and the least is that for December. 



Atmospheric Pressure. 

 TABLE XVIII.— Daily, Weekly, and Monthly Means of the Height of the Barometer in 1844. 



