Intelligence and Miscellaneous Articles. 211 



impossible can be more or less clearly imagined by the 

 mathematician. 



It must not be forgotten that beside the resolution into 

 plane waves dealt with above, there are an infinite number of 

 resolutions into waves of other forms which are equally pos- 

 sible, and several of which present themselves in optical 

 inquiries. 



I am, Gentlemen. 



8, Upper Hornsey Rise, N., Vei T faithfully yours, 



July 14, 1897. Gr. JOHNSTONE Sl'ONEY. 



XXXI. Intelligence and Miscellaneous Articles. 



SOME OBSERVATIONS ON A NICKEL STRESS TELEPHONE. BY 

 F. J. JERVIS-SMITH, M.A., F.R.S., MILLARD LECTURER, TRINITY 

 COLLEGE, OXFORD. 



A T page 26 of the present volume of the Philosophical Maga- 

 ^*- zine a Nickel Stress Telephone is described by Messrs. Garrett 

 and Lucas. When I was working in 1891 on the magnetization 

 of wires of iron, steel, and nickel, which had received a permanent 

 set, I found that excellent telephonic effects couhl he produced by 

 means of wires under stress (p. 395, Phil. Mag. 1891, vol. xxxii.). 

 The authors of the paper mention the difficulty of comparing the 

 speaking-powers of different instruments. I expect that a form of 

 electrodynamoineter, which was shown in the Electrical Exhi- 

 bition in Paris of 1881, would be found of use in comparing the 

 relative outputs of different kinds of telephonic apparatus. The 

 instrument was constructed thus: — a small light coil, carried on 

 a balanced arm hanging by a bifilar suspension, moved over a 

 curved solenoid which passed through it. The alternating current 

 generated by a telephone when transmitting a musical note gave 

 a large deflexion of a light straw pointer attached to the suspended 

 arm. 



Oxford, July 2, 1897. 



ON THE INTERFERENCE, AND THE ELECTROSTATIC DEFLEXION 

 OF KATHODE RAYS. BY PROFESSOR JAUMANN. 



Two parallel kathode plates at a distance of 2 cm. from each 

 other are connected by a wire loop 250 cm. in length, and the 

 negative current of an induction machine is passed by means of a 

 sliding contact. By displacing this along the loop, with a suitable 

 adjustment the bright sharp plane is displaced in which the two 

 blue kathode lights interfere without becoming essentially broader. 

 This, being an action of a slight difference in the conducting 

 circuits to the kathodes, cannot be explained otherwise than as an 

 interference of the kathode lights. The simple interference 



