T H E 

 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



AND 



JOURNAL OF SCIENCE. 



[SIXTH SERIES.] 



MAY 1919. 



XLII. On a possible means of determining the tivo cJiaracterist it- 

 Constants of the ^Etlier of Space. By Sir Oliver Lodge, 

 F.R.S* 



[This elementary paper has for its object the eliciting of an 

 opinion, not the communication of a result.] 



THE two constants which regulate the properties and 

 behaviour of the aether so far as known, whether 

 the phenomenon studied be electric, magnetic, or optical, 

 are simplv and fundamentally defined thus, in terms of 

 actual mechanical force : — 



F = £ and ¥ = '"4. 

 rv?' w fjur- 



These definitions are independent of any system of units 

 (t-. e. are true in all), so the dimensions of an electric charge 

 are e = ly/(KF) and of a magnetic pole m=l v /(fiF). 



We may also write magnetic moment ml—fiAI, A being- 

 area and I being dejdt ; or we may equally well write 

 m/e = fiv; which happens to be of the same dimensions as the 

 coefficient of electrical resistance. 



The dimension of an induction coefficient is /jlI, and of a 

 capacity is K/. 



In the case of energy all unknown dimensions disappear, 

 since all forms of energy are interchangeable ; hence JLP 

 and -|SV 2 , or ml and e\, are truly dynamical expressions. 



* Communicated by the Author. 

 Phil. Mag. S. 6. Vol. 37. No. 221. May 1919. 2K 



