18 Mr Forbes on Polar Temperature. 



surprise at the coincidence of observations, with principles de- 

 duced from such experiments, which could only be repeated on 

 the small scale.* But what makes me farther regret the ap- 

 pearance of the article m No. ix. of your Journal, is, that the 

 demonstration from the logarithmic formula had actually been 

 given by Mr Ivory in the paper to which I allude, — not, how- 

 ever, for the purpose of showing that Professor Leslie's formula 

 was incorrect, because it deviated from the law of strict pro- 

 portionality to the heights, — but to point out the relation which 

 it bore to such a law,— a law which, I believe, is now supported 

 in all its generality by few philosophers. Let the formula, 

 therefore, be examined on its own merits, such as they are ; 

 but let it not be condemned as a mere rude approximation to 

 a known law given under a new form. I may also add, that, 

 instead of referring it to the barometer, as in the expression 



26 ( -n ), Professor Leslie now puts it under the more 



correct form of 25 ( - — J where 6 is the density of the air, 



which includes the influence of temperature. 



Having thus acquitted myself of what I considered it my 

 duty to do when I was enabled fully to clear up the facts of the 

 case which had recently engaged my attention, I take this 

 opportunity of saying a word or two upon another speculation 

 of the same philosopher, which I am afraid has less ground in 

 experiment than the so called " delicate and patient research. " 

 Whilst I saw Professor Leslie's opinions on the Mean Tem- 

 perature of the Pole confined to purely scientific works, I had 

 comparatively little anxiety to attempt to show their fallacy, 

 because the few who might there peruse them could in some 

 measure be considered as judges of the data upon which they 

 were founded. But when I see the same theoretical deduc- 

 tions brought forward in support of assertions, against which 

 conclusive experiments strongly militate, in a work of a purely 

 popular character, and of considerable circulation, -J- I could 

 have wished to see the question brought forward in its true 

 light by some one more competent to the task than myself ; 



* Philosophical Magazine, 1821. 



t Edin. Cabinet Lihrari/, Polar Regions, p. 12. 



e 



