﻿Vibrational Responders under Compound Forcing. 573 



valency electrons belonging to the outermost shell. From 

 the experimental data of this paper it could be proved that 

 this is really the case (Part V. §§ 2 and 3). 



In Part V. § § 6-9 a theoretical discussion has been given 

 of the non-diagram lines and of the fine structure of the 

 absorption discontinuities. An experimental proof has been 

 given that part of the non-diagram lines are emitted by 

 atoms which have lost more than one electron at the same 

 time by an impact with one single high-speed /3-particle 

 (Part V. § 7). Furthermore, an explanation has been given 

 of some non-diagram lines which lie at the long- wave-length 

 side of diagram lines, and it has been suggested that these 

 lines should appear at the same time in the emission and in 

 the absorption spectrum (Part V. § 9). 



I am much indebted to the kindness and interest of 

 Prof. M. Siegbahn and Prof. N. Bohr. 



LI. Vibrational Responders under Compound Forcing. By 

 Prof. E. H. Barton, F.R.S., and H. M. Browning, 

 Ph.D.* 



[Plates III. & IV.] 



IN p'revious papers f, experiments were described in which 

 sets of responders were under double forcing, but these 

 forces were quite independent of each other. The present 

 paper deals with cases in which the vibrational responders 

 in use are under forcing, either (1) from the compound 

 harmonic motion of a single-pendulum driver, or (2) from 

 the associated motions of two coupled pendulums. 



In the first case they illustrate the analysis of a musical 

 tone by the mechanism of the ear on the resonance theory of 

 audition. In the second case they show the double resonance 

 sometimes observed when dealing with two electrical circuits 

 closely coupled, or two communicating resonating chambers 

 used with thermophones. 



Compound Harmonic Vibration. — To illustrate by a set of 

 responders the analysis of a compound harmonic vibration, 

 the apparatus was arranged as shown in fig. 1. A stout 

 cord ACB is fixed at iV and B and set in motion by the 

 swinging of the pendulum CD. The mass of the bob D is 

 made paramount, in order that it maybe used as the driver %. 



* Communicated by the Authors. 



t Phil. Mag. vol. xxxvii. pp. 453-455, April 1919, and vol. xxxviii. 

 pp. 163-173, July 1919. 



\ From this it follows that ABCD keeps the shape shown during 

 vibration of 1) ; hence the virtual length of this driving pendulum is EI). 



