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Data towards determining the Decrease 



amply meriting more attention than appears to have been 

 hitherto bestowed upon it. The following data will furnish 

 a commencement to any one willing to undertake the task of 

 observation and experiment on this head. 



1. Temperature of the Atmosphere, — Sir Thomas Brisbane 

 and Mr. William Galbraith have brought together a few 

 observations {Edin, New Phil. Journal, Nov. 1832 — Jan. 1833), 

 by which it appears that the thermometer falls 1° of Fahren- 

 heit in 212 ft. of ascent for heights of 2000 ft. or 3000 ft. 

 Thus: — 



Ben Lomond, from Edinburgh, gave 243 ft. 



Ben Lomond, from Rowardennan (its base) 205 

 Ben Nevis and its base - - 216 



Carnethie and Edinburgh - - - 183 



Cheviot and Holy Island - - 212 



Average - - 212 



In the Edinburgh New Philosophical Journal (Jan. — April, 

 1833) I have published a series of observations, made in July 

 and August, 1832, on the temperature of the Highland 

 mountains. By these it appears, that, with a mean difference 

 in elevation of 2055 ft., the mean difference of temperature 

 was 9^° Fahr. Dividing the former by the latter, we should 

 get only 216 ft. of ascent for 1° of temperature. The true 

 average, however, should be drawn from the mean of the 

 number of feet required to sink the thermometer 1° on the 

 different days. The following are my results : — 



The observations at the upper stations were usually made 

 between 1 and 3 p.m. ; those at the lower stations preceding 

 or following them by from two to six hours ; more usually by^ 

 only two or three. This would, of course, give an excess of 



