On the Objective Reality of Combination Tones. 341 



Table of the principal Symbols used. 



The suffix 1 refers to the dielectric ; the suffix 2 to the plate. 

 In our case, where all media are assumed to be non-magnetic, 



j3 = dielectric constant, 

 a = 4?r X conductivity. 



b— ratio of the reflected to the incident amplitude at the first 



surface of the plate. 

 e — the corresponding ratio at the second surface. 

 c= ratio of the refracted to the incident amplitude at the first 



surface. 

 /=the corresponding ratio at the second surface. 

 d= thickness of slab. 

 X l= wave-length in dielectric. 

 X 2 = „ „ electrolyte. 



— \p =the change of phase on reflexion at the first surface. 

 — ^'= „ „. refraction thro ugh the second surface. 



p= — jPi + ^2 * s defined by (4). 

 : rj, x are defined by (9). 



X gives the rate of damping of the wave-train, being 90° for 

 a steady ray. 

 jo, 6 are defined by (10). 



r is 

 fc, a are 



S is 

 o>, £ are 

 (p is 

 A „ 



55 



5, (11). 



55 



„ (33). 



55 



,5 (36). 



55 



,5 (41). 



55 



„ (42). 



55 



„ (67). 



t it _ intensity of transmitted ray 



intensity of incident ray 

 j it _ intensity of reflected ray 

 intensity of incident ray 



XXXI LI. On the Objective Reality of Combination Tones. By 

 A. W. Kucker, M.A., F.R.S., and E. Edser, A.R.C.S.* 



THE question of the objective existence of combination- 

 tones has been keenly disputed. At first they were 

 regarded as produced within the ear itself. Yon Helmholtz 

 in part adopted this view, and gave a theoretical explanation 

 of the way in which the construction of the ear might lend 

 itself to such a result. (' Sensations of Tone/ App. XII.) 

 He also believed that they existed objectively when the 



* Communicated by the Physical Society : read March 22, 189o. 

 Phil. Mag. S 5. Vol. 39. No. 239. April 1895. 2 A 



