27*2 On the Meteorology of England in the year 184-7. 



counties of Cornwall and Devonshire, and also, though at a 

 less rapid rate, in the northern latitudes, the temperatures of 

 September and October at intermediate places were nearly of 

 the same value. 



It was found that the months from March to July were less 

 humid than the average for the year, and that the remaining 

 months were more humid than the yearly average. The 

 months of March to July are those distinguished by the tem- 

 perature of the air increasing, and those from August to 

 January or February by a decreasing or stationary tempera- 

 ture. The places situated in the counties of Cornwall and 

 Devonshire were less humid than elsewhere; for notwith- 

 standing the greater amount of vapour contained in the same 

 mass of air in those counties to that in other places, yet the 

 temperature increased more rapidly than the air received the 

 addition to its vapour necessary to keep an equal degree of 

 humidity. 



The following Table contains the mean of all the monthly 

 values of each element : — 



From the numbers in this table the following values have 

 been deduced for the year 1847: — 



The mean pressure of the atmosphere of dry air at the level 

 of the sea was 29*641 inches. This value applies to all parts 

 of the country. 



The mean pressure of the atmosphere of vapour in latitude 

 51° so' was 0"319 inch; and this value seems to diminish 

 O'OIO inch for an increase of 1° in latitude. 



The mean temperature of the air at the level of the sea 

 in latitude 51° 30' was 50^^ O'; and this value at a uniform 

 level was found to vary 1° very nearly for a change of 1° of 

 latitude. 



No certain law can be deduced from the observations of 

 1847, representing the excess of the temperature of the air 

 above those of evaporation and dew-point; depending upon 

 the difference of latitude, it seems however that the excess be- 

 comes smaller as we proceed north ; but the observations of 

 the wet-bulb thermometer during the early part of the year 

 1847 were unsatisfactory in many places, and the following is 

 all the information I can give in this respect: — 



The mean excess of temperature of the air above that of 

 evaporation was 3°'0, and above that of the dew-point was 

 S°'Q^ in the counties of Cornwall and Devonshire; 



The mean excess of temperature of the air above that of 

 evaporation was 2°'2, and above that of the dew-point was 

 4°'7, at places situated in the vicinity of the sea; 



The mean excess of temperature of the air above that of 



