316 Geological Society : — 



radiations are allowed simply to fall on a plate communicating 

 with the electrometer, after the plate has been for an instant 

 put to the earth, a deflection is slowly formed, which is posi- 

 tive with the bodies as yet studied. It seems that in such a 

 case the bodies surrounding the plate replace the metal net; 

 it is therefore probable that negative electricity goes to these 

 bodies and thence to earth. 



(d) If A is a brass disk covered with crystalline selenium, 

 it appears that it is at first electronegative to gas-carbon, 

 and that coupling it with a metal net' can form a photo- 

 electrical cell. 



But when the ultra-violet rays are suppressed so as to 

 prevent the occurrence of the phenomenon described, it can 

 then be recognized that the other rays are producing a varia- 

 tion of the electromotive force of contact between the selenium 

 and any other metal, making the selenium more electro- 

 negative than when it is in darkness. 



Putting aside this last phenomenon, which is of a different 

 kind to those described in a, b, c, and without pretending 

 to attempt to give a complete explanation, which at present 

 would be premature, it seems to me that the idea is at least 

 provisionally acceptable of an electrical convection, provoked 

 by ultra-violet radiations, from bodies on which exists an elec- 

 trical distribution of a given sign (negative probably), caused 

 by electromotive forces of contact, towards those on which 

 exists an electrical distribution of contrary sign (positive) due 

 to the same cause. 



XLII. Proceedings of Learned Societies. 

 GEOLOGICAL SOCIETY. 

 [Continued from p. 242.] 



January 25, 1888.— Prof. J. W. Judd, F.R.S., President, 



in the Chair. 



rPHE following communications were read : — 



■*- 1. "On Ailurus anglicus, a new Carnivore from the Red Crag." 



By Prof. W. Boyd Dawkins, M.A.,F.R.S.,F.G.S. 



2. " A Contribution to the Geology and Physical Geography of 

 the Cape Colony." By Prof. A. H. Green, M.A., F.E.S., P.G.S. 



The account given in this paper of the geology of Cape Colony was 

 founded on observations made during a visit to the country of four 

 months' duration for the purpose of reporting upon the coal. A con- 



