223 



The station where the meteor was seen is situated very nearly in 

 latitude 56° 13' 5" K, longitude 12^ 2s- 6 W. 



It is worthy of remark, that as the meteor was seen at 11^ 15"^, 

 Greenwich mean time, if allowance is made for the longitude of the 

 station and the equation of time, it follows that it appeared about 48™ 

 before apparent noon, or about that time of day when the sun shines 

 most brightly. Now, while many accounts are extant of meteors which 

 have appeared during the day, and have attracted attention by explod- 

 ing audibly, or have been accompanied by the descent of meteoric stones, 

 I was not aware that any object like the meteor of the 30th September, 

 resembling so closely the more tranquil phenomena of shooting stars, 

 had been described as being seen within an hour of noon, and in 

 bright sunshine. I was, therefore, desirous of obtaining other observa- 

 tions of the meteor, and for that purpose I sent a short account of it to 

 one of the Edinburgh newspapers, requesting the favour that any ob- 

 servations of it made elsewhere might be communicated to me, in 

 order that they might be incorporated with this narrative. I have 

 not, however, had a single communication on the subject, — a result 

 which, although it is to be regretted, yet does not surprise me ; for, 

 from the faint illumination of the meteor, it was an object which 

 would scarcely attract observation, although it was easily perceptible 

 to an eye which, like my friend's, was already directed to the region 

 of the sky where it appeared. 



3. On the Mechanical Action of Heat. By "W. J. Macquorn 

 Rankine, C.E., F.H.SS. Lond. & Edin., &c. 



Section VI. Subsection 4. — On the Thermic Phenomenon of Cur^ 



rents of Elastic Fluids. 

 Supplement. — Of a Correction applicable to the results of the 



previous reduction of the experiments of Messrs Thomson and 



Joule, 



In investigating the phenomena of the free expansion of gases in 

 the previous part of this paper, they had been considered as expand- 



