193 



May 2, 1861. 



Major-General SABINE, R.A., Treasurer and Vice-President, 

 in the Chair. 



In accordance with the Statutes, the names of the Candidates re- 

 commended by the Council for election into the Society, were read 

 from the Chair, viz. 



Charles Spence Bate, Esq. 

 Heinrich Debus, Esq. 

 Campbell De Morgan, Esq. 

 Thomas A. Hirst, Esq. 

 A. Matthiessen, Esq. 

 J. Clerk Maxwell, M.A. 

 Ferdinand Miiller, M.D. 

 William Newmarch, Esq. 



Edmund Alexander Parkes, M.D. 

 William Pole, Esq. 

 Philip Lutley Sclater, M.A. 

 Charles Frederick Alexander 



Shadwell, Capt. R.N. 

 Henry J. Stephen Smith, M.A. 

 William Stokes, M.D. 

 George Johnstone Stoney, M.A. 



The following communications were read : 



I. " On Internal Radiation in Uniaxal Crystals." By BALFOUR 

 STEWART, Esq., A.M. Communicated by J. P. GASSIOT, 

 Esq. Received April 11, 1861. 



(Abstract.) 



The well-known theory of exchanges, which was proposed by the 

 late Prof. Prevost of Geneva, is built upon the fact that a substance 

 placed anywhere within an enclosure of a constant temperature will 

 ultimately attain the temperature of the enclosure. 



In his theory M. Prevost supposes that a constant, mutual, and 

 equal interchange of radiant heat takes place between the body and 

 the enclosure which surrounds it, so that, receiving back precisely 

 that heat which it gives away, the former is enabled to remain at a 

 constant temperature. 



With respect to this radiation, which is thus supposed to be con- 

 stantly taking place between substances at the same temperature, it 

 had until lately been conceived of as proceeding mainly, if not en- 

 tirely, from the surface of bodies a very thin film or plate of any 



