215 



Ordinary Meeting, March 18th, 1862. 

 J. C. Dyer, Esq., Vice-President, in the Chair. 



The following communication from Sir John F. W. 

 Herschel, Bart., M.A., D.C.L., F.R.S., &c.. Honorary 

 Member of the Society, was read by Mr. Baxendell: — 



In the report of the Ordinary Meeting of the Literary and 

 Philosophical Society for February 18, 1862, I find an 

 abstract of a paper " On the Present State of Meteorology," 

 by Mr. T. Hopkins, M.B.M.S., in which he is reported to 

 state that in my recent work on Meteorology I ''^omit to 

 notice the disturbing influence of the liberated heat of con- 

 densing vapour on the gases," and also that in that work I 

 " abandon the old theory of winds " (meaning, I presume 

 from the context, the Hadleian theory,) *' and attribute them 

 to the action of aqueous vapour in a new form." 



With regard to the former of these two statements I beg 

 to refer to Art. 5o of that work, where, alluding to the con- 

 densation of the vapour in the atmosphere, it is remarked 

 that " in every case, such condensation is accompanied with 

 a mitigation of cold at the point where it actuallij takes place. ^^ 

 What effect beyond this the condensation of vapour can pro- 

 duce on the gases I am at a loss to understand. It can in 

 no case give rise to an actual elevation of temperature above 

 that of the mixture of air and vapour which may be intro- 

 duced into any mass of cold air and which may thereby effect 

 a partial condensation. It can only act in mitigation of the 

 chilling effect of such admixture on the introduced portion 

 which would arise were the vapour not condensed. Inasmuch, 

 however, as its condensation and precipitation as rain 

 diminishes joro tanto the total barometric pressure, and there- 

 fore allows both air and vapour to flow in from other quarters , 

 Proceedings— Lit. & Phil. Society— No. 13.— Session 1861-^62. 



