﻿Intelligence and Miscellaneous Articles. 1063 



ON DAMPED VIBRATIONS. 



To the Editors of the Philosophical Magazine. 

 Gentlemen, — 



The note in Phil. Mag. July 1922, p. 284, entitled" Note on 

 Damped Vibrations " gives a somewhat inadequate account of 

 a problem treated in detail by liouth, ' Dynamics of a Particle' 

 (1898 ed.) p. 66. 



As a dynamical problem, the chief point of interest seems to 

 have been overlooked by the author of the above note, namely, the 

 discontinuity rendered possible hj the assumption of constant 

 friction (ltouth, L c). 



Some further results are easily obtained in this direction ; thus 

 if the particle is placed at rest at distance a? from the origin it 

 will execute n semi-vibrations (about alternative centres), where 

 n is the least integer determined by \x Q \ — 2«.F/c a < F/c 2 ; if the 

 particle is projected with any velocity, | # d | may be taken to refer 

 to the first position of rest attained. 



This excludes an easily determinable portion of the series of 

 semi-circles considered in the note. 



The extended problem, including friction proportional to the 

 velocity, is discussed by J. Audrade, Oomptes Rendus, 5 Jan. 1920. 



Artillery College, Woolwich. C. E. Wright. 



July 18, 1922. 



THE MAGNETIC PROPERTIES OF THE 

 HYDROGEN-PALLADIUM SYSTEM. 



To the Editors of the Philosophical Magazine. 



Gentlemejn, — 



In a Paper communicated to the Royal Society (Proc. A, vol. 

 101, p. 261, 1922), I described a number of experiments on the 

 measurement of the specific magnetic susceptibility of samples of 

 palladium-black which had been charged with different amounts 

 of hydrogen. The results showed that the susceptibility 

 decreased rapidly with increase of hydrogen content. 



My attention has just recently been directed by Mr. H. F. 

 Biggs to a research carried out by him and described in the 

 Philosophical Magazine, xxxii. p. 131 (1916). The latter experi- 

 ments were made on a sample of palladium-foil, the susceptibility 

 of which was found to decrease very considerably with increase of 

 hydrogen content, my results for palladium-black thus agreeing 

 with his on crystalline palladium. Mr. Biggs' work had entirely 

 escaped my notice, the only experiments on the magnetic pro- 

 perties of crystalline palladium of which I was hitherto aware 

 being those of Graham (Jour. Chem. Soc. vol. xxii. p. 430, 1869). 

 Graham's deductions seemed so extraordinary, in the light of 

 what is now known about the magnetic property of free and 



