914 Intelligence and Miscellaneous Articles. 



Finally, in the last figures a variable current of lower 

 frequence (about 50 periods per second) is reproduced. 



There is no doubt that the general form is fairly correct. 

 But even in this case a detailed accuracy has not been 

 ascertained. In fig. 10 (PL XVI.) the vibrations of higher 

 frequency, which arise from the free vibrations of the 



Fisr. 11. 



membrane, can be observed. A measurement of their periods 

 showed that they were engendered by the commutator of the 

 generator. As regards the foregoing examples, it is probable 

 that their amplitudes are greater in the reproduction than 

 they actually are. 



As a general result of this investigation, we may state that 

 the telephone can not be utilized for oscillographic purposes. 



Ortofta, Dec. 10, 1913. 



C. Intelligence and Miscellaneous Articles, 



John Heney Poynting. 



ALTHOUGH Prof. Poyntiug, whose loss will be universally 

 deplored, graduated with high distinction in mathematics 

 at Cambridge, coming out as third wrangler in the tripos of 

 1876, his interest seems always to have lain in the direct eluci- 

 dation of physical laws and principles rather than in the evolution 

 and exposition of their consequences by analysis. When he 

 came to Cambridge, in 1872, he was already largely trained in 

 the niceties of refined experimentation ; and after graduation he 

 embraced an early chance to resume experimental work at Man- 

 chester. The founding of the Mason University College gave 

 him the opportunity of organising a laboratory of his own. Much 

 of his work about this time was concerned with instrumental im- 

 provements, such as the design of polarimeters and other appa- 

 ratus ; and to the same period belong studies in chemical physics, 

 such as the elucidation of osmotic pressure, theories to which in 

 later years he returned with conviction, and which, though per- 

 haps not yet fully appreciated, should not be Jost sight of, in 

 view of his proved insight into fundamental problems in other 

 domains. An example of the latter is the memoir on the transfer 

 of energy in the electromagnetic field, Phil. Trans. .1884, which 

 culminates in the famous result that will go down to posterity 

 as Poynting's Theorem, which not only specifies the path of transfer 

 of electric energy from one material system to another through 



