M. Dulong's Researches, fyc. 211 



The very same appearance continued to present itself until 

 the warm weather began ; but the atmosphere was then so 

 hazy as to obscure the mountain altogether during its con- 

 tinuance, nor have the rains, which are only just setting in, 

 brought them yet within view. 



I am not in the habit of observing, and still less of describ- 

 ing, the phenomena of nature, and I fear you may not fully 

 comprehend the impression which I wish to convey ; but if 

 you figure to yourself a vast column of smoke rushing violent- 

 ly from the flue of a strong furnace, black at the bottom, and 

 burning clearer as it ascends, and the wind dispersing the top 

 of the shaft when it rises above the influence of the fire, and 

 you will have its appearance in a few words. 



The peak on which this phenomenon is seen, is that remark- 

 able rocky one due north of Rungapannee, and the most ele- 

 vated of the whole range seen from thence. But I am of opi- 

 nion that, if it really be a volcano, the crater is situated on 

 the north side of the highest point, because when the smoke 

 was seen the peak on our side was distinctly visible, and the 

 smoke seemed to me behind it. It is probable that some 

 lower eminence, concealed from us by the highest point, may 

 be the seat of it. 



It is hardly possible to believe that the appearances now 

 described can arise from a cloud, as it is not usual for clouds 

 to retain the very same form and shape for months together, 

 nor to appear in the same identical spot, The summits of all 

 the other peaks remained clear and bright as usual during the 

 whole time that the smoke was observed. 



Akt. IV. — Researches on the Refractive Power of Elastic 

 Fluids. * By M. Dulong. 



1 he object of these researches, was to ascertain if the refrac- 

 tive power of gases followed any law analogous to that which 

 had been found for their specific heats, and if the act of com- 



* This paper is a Translation and Abstract of an Account of M. Dulong's 

 Kescarches, given in the Now. Hull, des Sciences, September 1825. 



