in the year 1847. 275 



The mean additional weight required to saturate a cubic 

 foot of air was 0*9 grain in the counties of Cornwall and 

 Devonshire, and 0'7 grain at other places. 



The mean degree of humidity was 0'825 in the counties of 

 Cornwall and Devonshire, and 0*839 at other places. 



The mean weight of a cubic foot of air at all places at the 

 level of the sea was 541 grains. 



The preceding results are chiefly for one point only, viz. 

 that of the Royal Observatory at Greenwich reduced to the 

 level of the sea. To render the results most generally useful, 

 I have deduced the following formulae, applicable to any place 

 in England, taking into account the irregularities of the for- 

 mation of the surface of the soil, and the law of the decre- 

 ment of heat with increasing elevation. 



The pressure of dry air at any place in England in the 

 year 1847 was 

 *°' height of place in feet above the level of the sea 



^y 0*1 ~r~" . j • 



82 mches 



The pressure of water was Qii^'Sig + (51° 30'— latitude) x 

 0-010 inch. 



The sum of the two preceding formulae gives the reading 

 of the barometer. 



The temperature of the air at any place in England may be 

 calculated from the formula — 



50°-0 + (51° 30'— latitude) x 1°— 0-00345° X height of place 

 in feet above the level of the sea. 



The observations are not sufficient to deduce the term de- 

 pending upon longitude ; its coefficient however would be 

 very small, and in the present state of our knowledge may be 

 neglected. 



The approximate yearly range of temperature may be cal- 

 culated from the formula — 



78°+ (51° 30'-latitude of place) x 5°. 



The mean monthly range of temperature may be calculated 

 from the formula 



40° + (51° 30'- latitude of place) x 3°. 



The mean daily range Of temperature may be computed 

 from the formula 



16°-2 + (51° 30*- latitude of place) x 1°. 



The approximate weight of a cubic foot of air may be cal- 

 culated from the formula 



- . , . . height of place in feet above the level of the sea 



541 grams + — ^ C ^ . , . 



^ 82 mches 



T2 



