Royal Society, 553 



part in the currents of telegraphic wires. Therefore, although 

 proceeding from the same cause, these two kinds of phenomena, 

 notwithstanding that they are subject to the same general varia- 

 tions, present remarkable differences in their phases. 



I will add that I have failed to discover how it is that, under 

 conditions apparently perfectly identical, the discharge takes 

 place at one of the poles sooner than at the other, or, what is 

 still more remarkable, why, after occurring for some time at one 

 of the poles, it passes suddenly to the other : the changes are 

 evidently attributable to certain modifications which occur in the 

 medium placed in the course of the discharge, and the nature of 

 which it is difficult to determine ; but they readily explain how 

 it happens that in nature, where it is impossible to admit that 

 the conditions are identical and constantly the same at the two 

 poles of the earth, the aurorse, although manifesting themselves 

 simultaneously at one and the other, can never be completely 

 alike in both. They also render obvious how it is that when 

 they are observed at a single pole (at the north pole, for instance) 

 they exhibit in their appearance, as well as in the phenomena 

 which attend them, those oscillations which are their principal 

 characteristic. 



Supplemental Note. — I am desirous of mentioning here that 

 the delicate apparatus by which I have succeeded in faithfully 

 reproducing the aurora? boreales and australes with their atten- 

 dant phenomena, has been constructed in the manufactory of 

 philosophical instruments of Professor Thury, under the direc- 

 tion of M. Eugene Schwerd, a skilful German artist. This 

 apparatus, executed with the greatest care, may be applied to a 

 number of experiments ; I have especially used it with success 

 in researches on the propagation of electricity in different gases 

 — researches which I shall soon publish. 



LXXVT. Proceedings of Learned Societies. 



ROYAL SOCIETY. 

 [Continued from p. 492.] 

 June 13, 1861.— Thomas Graham, Esq., Master of the Mint,V.P., 

 in the Chair. 



THE following communications were read : — 

 " On the Bromide of Carbon." By Arthur C. W. Lennox, 

 Esq. 



" On the Action of Dibromide of Ethylene on Pyridine." By 

 John Davidson, Esq. 



" On a New Class of Organic Bases, in which Nitrogen is substi- 

 tuted for Hydrogen. " By Peter Griess, Esq. 



In a previous Note I have called attention to two new bodies pro- 



