CLIMATE. 



27 



The influence of elevation above the sea level, in de- 

 pressing the temperature, has been very little attended to 

 in Britain. Sir Thomas Brisbane and Mr. Galbraith 

 (Edin. New Phil. Journal) have estimated the decrease 

 to be 1° of temperature for 212 feet of ascent, in latitude 

 55° — 57° ; while my own estimates (Mag. Nat. Hist, 

 vol. vii. p. 444.) raise it to 239 feet between 53° — 59°. 

 These estimates do not refer to the winter months ; nor 

 is either of them worthy of implicit reliance. For the 

 convenience of whole numbers we may call them 70 and 

 80 yards for 1° of temperature ; and then assuming 48° as 

 the temperature at the sea level, with an even decrease in 

 ascending, the following scale will exhibit the supposed 

 temperature of the mountain atmosphere, between lati- 

 tudes 53° — 57°; but on the northern side of the Gram- 

 pians, beyond the line of 57°, we may deduct at least 

 one degree. 



SCALE OF SUPPOSED TEMPERATURE OF THE AIR ON THE 

 MOUNTAINS OF BRITAIN. 



Temp. 



Elevation. 



Temp. 



Elevation. 





Yards. 



Yards. 





Yards. 



Yards. 



47° 



at 80 or at 



70 



37° 



at 880 or at 



770 



46 



160 



HO 



36 



960 



840 



45 



240 



210 



35 



1040 



910 



44 



320 



280 



34 



1120 



980 



43 



400 



350 



33 



1200 



1050 



42 



480 



420 



32 



1280 



1120 



41 



560 



490 



31 



1360 



1190 



40 



640 



560 



30 



1440 



1260 



39 



.1 720 



630 



29 







1330 



38 



800 



700 



28 







1400 



The corrected mean temperature of Lead Hills at 

 426 yards is 44±° ; that of Carbeth at 160 yards is 46J°. 

 Both accord better with the allowance of 80 yards for 1° 

 of temperature; but they are considerably at variance 

 from the above scale. In fact, the mean at Lead Hills 

 allows only 1° of temperature for 122 yards of ascent, 

 c 2 



