Theory of the Suspension of Clouds. 361 



I hope that a meteorological society may be formed ; and 

 wish it, if formed, every possible success. 



109. York Street, Whitechapel, London, June 3. 1836. 



[The United Service Society (see next Number), which has 

 members in many parts of the world, and some local com- 

 mittees in Britain and abroad, might, one would think, 

 render itself a very efficient agent towards the promotion 

 of man's progress in meteorology. The conductors of the 

 Society have taken cognisance of this subject to the following 

 extent: — " It is proposed to keep a meteorological journal at 

 the museum, for which purpose necessary instruments will 

 be provided, and the results noted." This notice is in the 

 Council's Fifth Annual Report, 1836.] 



■ 

 Steffi 3o — i 



i 

 Art. IX. Considerations opposed to Mr. White's Theory of the 



Principles upon which Clouds are suspended, (p. 246 — 251.) By 



w. w. c. 



There appears to be considerable obscurity in the part 

 where Mr. White gives us his own ideas upon the subject. 

 He observes, that "a much larger portion of aqueous vapour, 

 it must be recollected, is held in an elastic form near the 

 surface of the earth, than in the more elevated regions of 

 the clouds. In high regions, even on the summits of high 

 mountains, atmospheric pressure opposes very little check to 

 the natural tendency of water to assume an aeriform state ; 

 consequently [?], the higher we ascend in the atmosphere, 

 the quantity of moisture which is held in solution goes on 

 diminishing, until we arrive at the precise altitude beyond 

 which the effect of diminished pressure predominates, and 

 the aqueous vapour goes on increasing." I really do not see 

 that Mr, White is warranted in drawing any such conclusions 

 from his premises. What does " the effect of diminished 

 pressure predominate" over? Dr. Dalton has proved, that 

 evaporation, and suspension of vapour in air, are owing, not 

 to any solvent power that the atmosphere possesses, but 

 solely to its temperature, inasmuch as the same quantity of 

 vapour rises in vacuo. In fact, the atmosphere, as Mr. White 

 has correctly remarked, retards evaporation by its pressure. 

 Mr. White observes, the quantity of moisture diminishes the 

 higher we ascend in the atmosphere ; owing, doubtless, in a 

 great measure to the diminution of temperature. What, then, 

 does he mean by the aqueous vapour going on increasing? 

 Mr. White supposes that " it not unfrequently occurs, that 



