294 Mr. L. C. Jackson on 



In the relation (3) — can be replaced by 



V a 77 ' 



71 .S ... 



V1= 77W-^ (4> 



V cy 1 



c 



For the first harmonic -p— — ^. By the use of a calibrated 



variable condenser Co any suitable smaller relation j^j- r 



can be chosen. Thus the number of maxima to be counted 

 is reduced and the operation with the circuit IV spared. 



The application of this method to closed circuits con- 

 taining known capacities and inductances gave results 

 in good agreement with those calculated by Thomson's 

 formulaa. 



The above method was also used for the exact deter- 

 mination of wave-lengths emitted by vertical antennae 

 and other radiating circuits, with distributed capacity and 

 inductance, used in radio-telegraphy. 



On board the ' Lorraine/ 

 Aug. 30, 1919. 



XXVIII. Variably Coupled Vibrations: Gravity-Elastic Com- 

 binations. Masses and Periods equal. By L. 0. Jackson, 

 F.P.S.L., University College , Nottingham *. 



[Plates VI. & VII.] 



I. Introduction. 



I^HE present paper is a continuation of the work of 

 Prof. Barton and Miss Browning (Phil. Mag. vol.xxxiv. 

 p. 246, vol. xxxv. p. 62, vol. xxxvi. p. 36) on the subject of 

 coupled vibrations. 



The coupled system treated in the following pages consists 

 of an elastic lath pendulum and a gravity pendulum, which 

 can be attached to the lath at different points along its length. 

 The degree of coupling of the pendulums thus depends 



* Commrmicated by Prof. E. IT. Barton, F.R.S. 



