261 



January 8th, 1849- 



REV. HUMPHREY LLOYD, D. D., President, 

 in the Chair. 



Viscount Dungannon, John Bell, Esq. ; Rev. James Bew- 

 glass LL.D.; Rev. Edward Dillon; John Carley, Esq. ; 

 Jonathan Pirn, Esq.; John Purser, Esq.; John L. Rickards, 

 Esq. ; and Henry Smith, Esq. ; were elected Members of the 

 Academy. 



Mr. Donovan read the first part of a paper " On the De- 

 flections of the Magnetic Needle, producible by contact of 

 Metals with each other, and by their attrition ; with some ob- 

 servations on the applicability of these deflections to the pur- 

 poses of telegraphic communication." 



It is known that, under certain circumstances, some metals 

 will, by contact, act on each other in such a manner as to 

 produce a deflection of the magnetic needle, which will be re- 

 versed when, instead of contact, attrition is employed. The 

 experiment is generally made with a mass of bismuth and a 

 mass of antimony, each connected with the binding screws 

 of a galvanometer. If these masses, one held in each hand, 

 be brought into contact, the needle will be deflected; but 

 if the masses be rubbed against each other, the needle will 

 veer round perhaps to an equal degree on the opposite side 

 of the magnetic meridian. 



Professor Erman, of Berlin, who has bestowed much atten- 

 tion to the subject, thus sums up the opinions current upon 

 it . «« Some observers" (he says), - who appeal to the authortiy 

 of Mr. Emmet, express what they consider to he the law of 

 this action, by saying that thermo-electricity of contact is 

 changed invariably into the opposite state by the friction ot 



