358 Dr. Barton and Mr. Lownds on Reflexion and 



densers of various sizes; but no attempt was made to give a 

 complete theory of the various phenomena involved, and by 

 careful quantitative observations compare experiment with 

 theory. This fuller examination one of us, who followed 

 von Geitler under the late Professor Hertz, at Bonn, deter- 

 mined to attempt when opportunity offered. The present 

 paper embodies the result of the work carried out during the 

 session 1898-99 at University College, Nottingham, and 

 advances the problem another stage towards complete solution. 



2. The phenomena are more complicated than might be at 

 first supposed. This is chiefly owing to the fact that the 

 wave-train, reflected by the condenser under examination, 

 passes and repasses between the point of reflexion and the 

 oscillator at the beginning of the line. Hence the effect to 

 be observed, owing to reflexion at any condenser, is a 

 function not only of the coefficient of that reflexion but also 

 of the other constants of the circuit. To avoid unnecessary 

 complication, the wave-train transmitted by the condenser is 

 always completely absorbed by a suitable bridge at the end 

 of the line. 



3. By placing the electrometer beyond the condenser, the 

 wave-train transmitted is determined, and by placing the 

 condenser far beyond the electrometer the wave-train re- 

 flected is measured. In order to determine the phase-lag 

 introduced in the reflected wave-train, the condenser is 

 placed in a number of positions, each of which is only a 

 short distance beyond the electrometer. We thus obtain 

 stationary waves by the interference of the incident and 

 reflected wave-trains, and these, explored by the electrometer, 

 exhibit the phase-change sought. To bring this change of 

 phase into clearer relief, stationary waves are also obtained 

 by a resistance-bridge, whose reflexion coefficient is the same 

 as that of the condenser, but whose phase-change is it 

 simply. 



4. The results obtained with the three condensers used are 

 all in fair accord with theory, both as to phase-lag and 

 coefficient of reflexion and transmission. The experimental 

 discrepancy, if such it can be called, is in the direction of 

 less reflected and less transmitted than the long-wave theory 

 predicts. 



It may be mentioned here that the experiments, though 

 given in this paper after the theory, were in practice finished 

 before the theory was fully worked out. The experimental 

 results are thus free from any bias due to anticipation based 

 on theory. Each set of readings was accepted simply on the 



