THE 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[FIFTH SERIES.] 



MARCH 1895. 



XXIII. Some Experiments icith Alternating Currents. By 

 Albert Griffiths, M.Sc, Berkeley Fellow of Owens 

 College, Manchester*. 



THIS paper embraces experiments on certain actions pro- 

 duced by an alternating current when it passes through 

 the coil or coils of a galvanometer, and investigations of a 

 peculiarity noticed by Lenard, viz., that the resistance of 

 bismuth in a strong magnetic field, when measured with an 

 alternating current and a telephone, is greater than when 

 measured with a steady current and a galvanometer : in 

 addition there are some theoretical considerations. 



As mentioned by Dr. Schuster in Phil. Mag. vol. xlviii. 

 1874, p. 340, it is found that if an alternating current and 

 constant current combined go through the coils of a gal- 

 vanometer, the deflexion of the needle is greater than that 

 produced by the constant current alone. 



In my experiments, an induction-coil supplied with Kohl- 

 rausch's apparatus for the determination of electrolytic 

 resistance was used as the source of the alternating current, 

 the interrupter of which was replaced, initially, by a tuning- 

 fork which gave 128 complete vibrations per second. 



The galvanometer employed was one of Edelmann's : there 

 is a pair of coils on each side of the needle which can be 



* Communicated by Prof. A. Schuster, F.R.S. 

 Phil. Mag. S. 5. Vol. 39. No. 238. March 1895. R 



