311 



condensation heat is developed in the atmosphere, which has the 

 effect of raising the temperature of the higher air above what it 

 would have been had the rate of decrease continued uniformly from 

 the earth upwards. 



There are several instances of a second or even a third sudden fall 

 in the dew-point, but any corresponding variation in the temperature 

 is not so clearly exhibited, probably owing to the total amount of 

 moisture in the air being, at low temperatures, so very small that 

 even a considerable change in its relative amount would produce but 

 a ?mall thermal effect. 



As the existence of the disturbance in the regular progression of 

 temperature now stated rendered it necessary, in order to arrive at 

 any approximate value of the normal rate of diminution with height, 

 to make abstraction of the portion affected by the disturbing cause, 

 each series was divided into two sections, the first comprising the 

 space below the stratum in which the irregularity existed, and the 

 second commencing from the point where the regular diminution of 

 temperature was resumed. It was then found that the rate of dimi- 

 nution was nearly uniform within each section, but that it was 

 somevN^hat greater in the lower than in the upper sections. 



On taking a mean of both sections for each series, giving each 

 section a value corresponding to its extent, it is found that; the 

 number of feet of height corresponding to a fall of one degree Fahr- 

 enheit is — 



On August 17 292-0 feet. 



August 26 290-7 „ 



October 21 291-4 „ 



November 10 312-0 „ 



The first three values being remarkably coincident, and the last dif- 

 fering from them by about jjth of the whole. 



The air collected in the ascents was analysed by Dr. Miller ; he 

 states that " the specimens of air do not differ in any important 

 amount from that at the earth at the same time, but contain a trifle 

 less oxygen. All of them contained a trace of carbonic acid, but 

 the quantity was too small for accurate measurement upon the small 

 amount of air collected." 



June 2, 1853. 



The EARL OF ROSSE, President, in the Chair. 



The Annual General Meeting for the Election of Fellows was 

 held. 



The Statutes respecting the election of Fellows having been read. 

 Admiral Sir Francis Beaufort, and James Walker, Esq., were, with 

 the consent of the Society, appointed Scrutators to assist the Secre- 

 taries in examining the lists. 



