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 LONDON, EDINBURGH, and DUBLIN 



PHILOSOPHICAL MAGAZINE 



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JOURNAL OF SCIENCE. 



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XXV. Some Problems concerning the Mutual Influence of 

 Resonators exposed to Primary Plane Waves. By Lord 

 Rayleigh, O.M., F.R.S* 



RECENT investigations, especially the beautiful work of 

 Wood on "Radiation of Gas Molecules excited by 

 Light" f, have raised questions as to the behaviour of a cloud 

 of resonators under the influence of plane waves of their 

 own period. Such questions are indeed of fundamental 

 importance. Until they are answered we can hardly ap- 

 proach the consideration of absorption, viz. the conversion 

 of radiant into thermal energy. The first action is upon 

 the molecule. We may ask whether this can involve on 

 the average an increase of translatory energy. It does not 

 seem likely. If not, the transformation into thermal energy 

 must await collisions. 



The difficulties in the way of answering the questions 

 which naturally arise are formidable. In the first place we 

 do not understand what kind of vibration is assumed by the 

 molecule. But it seems desirable that a beginning should 

 be made ; and for this purpose I here consider the case of 

 the simple aerial resonator vibrating symmetrically. The 

 results cannot be regarded as even roughly applicable in 

 a quantitative sense to radiation, inasmuch as this typhis 



* Communicated by the Author. 



t A convenient summary of many of the more important results is 

 given in the Guthrie Lecture, Proc. Pliys. Sec. vol. xxvi. p. 185 (1914). 



Phil. Mag. S. 6. Vol. 29. No. 170. Feb. 1915. P 



