694 



REPORT — 1893. 



the curve shown by T, fig. 4. It is thus seen that the lengths of the abnormal 

 parts which give maxima and minima are the same as in the corresponding optical 

 phenomena, but that the values of these maxima and minima, instead of being 

 respectively equal, as in optics, form a damped series fading away to a common 

 steady value. 



These interference phenomena may, of course, be experimentally obtained by 

 any of the changes in the wires which produce reflection. But the most striking 

 method which 1 have found is that of hanging sheets of tin foil upon the con- 

 ducting wires so as to form the abnormal part, as shown in fig. 3. The sheets of 

 tin foil were 32 cm. deep, the cross-pieces used for separating the wires and sheets 

 were of wood. 



The beginning of the abnormal part thus formed reflected a wave whose ampli- 

 tude is of the order 0'8 of that incident upon it. With this arrangement upwards 

 of 200 electrometer readings were taken, the final result of which is shown by the 

 upper curve marked E in fig. 4, the lengths of the abnormal parts being abscissae 

 and the intensities of the transmitted waves ordinates. It is noticeable that in 

 tig. 4 the theoretical curve lies wholly below the experimental one. The dis- 



FiG. 4. — Energy of transmitted waves. 



/rn. 



2 3 -f .'> 6 7 



Zj^fi^ihs of A7yrLorma7^ part fB-OFtz/t/. 



tOm.. 



crepancy, however, is no greater than can be accounted for by a known disturbance 

 which I have already measured, but have not yet succeeded in eliminating. The ex- 

 planation of this, together with an account of other experiments, I hope to give in 

 a future paper. 



The above work was carried out in the University of Bonn under the direction 

 of Prof. Hertz, whose invaluable advice I wish most heartily to acknowledge. 



9. On Interference Phenomena exhibited by the Passage of Electric Waves 

 through Layers of Electrolyte.^ By G. Udny Yule. 



This research was begun by the author with a view to try and definitely 

 answer the question whether electrolytes possess for rapid electric oscillations the 

 same resistance as for steady currents. Some attempts were first made to directly 

 improve the procedure used in 1889 by Prof. J. J. Thomson,- but the results were 

 unsatisfactory, and the following method, by which it was hoped absolute measure- 

 ments might be obtained, was finally adopted : — 



The electric waves (wave-length 9 metres) were propagated between a pair 



' Published in FMl Mag., xxxvi. (1893), pp. 531-545. 

 - Proc. Roy. Soc, xlv. 1889, p. 269. 



