93 



In the fourth part of the paper the author relates a great number 

 of experiments, which concur in proving that when a piece of metal 

 is moved in any particular direction, either in front of a single mag- 

 netic pole, or between the opposite poles of a horse-shoe magnet, 

 electrical currents are developed which pass along the substance of 

 the metal in a direction transverse to that of its own motion. By 

 the application of this principle, the author is enabled to explain 

 the various phenomena which take place in the experiments of 

 Arago and others, where magnetic action appears to be developed 

 by rotation ; and which have been erroneously attributed to simple 

 magnetic induction, and to the time supposed to be required for the 

 progress of that induction. The electro-magnetic effect of the elec- 

 tric current induced in a conductor by a magnetic pole, in conse- 

 quence of their relative motion, is such as tends continually to di- 

 minish that relative motion ; that is, to bring the moving bodies into 

 the state of relative rest ; so that if the one be made to revolve by an 

 extraneous force, the other will tend to revolve with it in the same 

 direction, and with the same velocity. 



A paper was read, entitled " Some Remarks on the internal Struc- 

 ture of the Platypus Anatinus (Ornithorhynchus paradoxus, Blum.)." 

 By Richard Griffin, Esq. Communicated by Dawson Turner, Esq. 

 F.R.S. 



Having an opportunity of examining two specimens of the Orni- 

 thorhynchus, the one male, the other female, belonging to the Norfolk 

 and Norwich Museum, the author found in the latter two large 

 mammary glands, one on each side of the chest, and covering nearly 

 the whole under surface of the animal; numerous ducts proceeded 

 from them, perforating the skin, at two circular portions, which pre- 

 sented no elevation corresponding to nipples. The Fallopian tubes 

 terminate by very small orifices in the cloaca : posterior to their termi- 

 nations the author observed two slightly projecting processes, con- 

 taining each the orifice of a duct which proceeds to a length of at 

 least two inches, but the continuation of which could not be traced in 

 the specimen examined in consequence of the injuries it had received. 

 In the male, three pointed processes were noticed at each extremity of 

 the corpora cavernosa of the penis, the cavities of which do not com- 

 municate with one another, and are separated before their termina- 

 tion. The spur of the male is furnished with a sac, of the size of a 

 pea, containing a poisonous fluid, which by means of a canal is con- 

 ducted into a wound inflicted by the spur. 



Decembers, 1831. 



HIS ROYAL HIGHNESS THE DUKE OF SUSSEX, K.G., 

 President, in the Chair. 



The Right Hon. Sir James Graham, Bart, was elected a Fellow 

 of the Society. 



A paper was read, entitled " Some Account of a New Volcano in 



H 2 



