Forced Vibrations of Electromagnetic Systems. 153 



should be aimed at is to get currents of any frequency reproduced 

 at B in their proper proportions, attenuated to tne same extent. 

 Change L to 5. Results : — 



1-437, 2-251, 3-176, 4-169, 4-670. 



Good telephony is now possible, though much distortion remains. 

 Increase L to 10. Results : — 



1-235, 1-510, 1-729, 1-825, 1-854. 



This is first class, showing approximation towards a non-distor- 

 tional circuit. Now this is all done by the self-induction carrying 

 forward the waves undistorted (relatively) and also with much less 

 attenuation. 



I should add that I attach no importance to the above figures 

 in point of exactness. The theory is only a first approximation. 

 In order to emphasize the part played by self-induction, I have 

 stated that by sufficiently increasing it (without other change, if 

 this could be possible) we could make the amplitude of current at 

 the end of an Atlantic cable greater than the steady current (by 

 the gwasi-resonance). 



Note C. 



In Sir "W. Thomson's article on the " Velocity of Electricity " 

 (Nichols's Cyclopcedia, 2nd edition, 1860, and Art. lxxxi. of 

 ' Mathematical and Physical Papers,' vol, ii.) is an account of the 

 chief results published up to that date relating to the " velocity " 

 of transmission of electricity, and a very explicit statement, except 

 in some respects as regards inertia, of the theoretical meaning to 

 be attached to this velocity under different circumstances. This 

 article is also strikingly illustrative of the remarkable contrast 

 between Sir W. Thomson's way of looking at things electrical (at 

 least at that time) and Maxwell's views ; or perhaps I should say 

 Maxwell's plainly evident views combined with the views which 

 his followers have extracted from that mine of wealth ' Maxwell,' 

 but which do not lie on the surface. [As charity begins at home, 

 I may perhaps illustrate by a personal example the difference 

 between the patent and the latent, in Maxwell. If I should claim 

 (which I do) to have discovered the true method of establishment 

 of current in a wire — that is, the current starting on its boundary, 

 as the result of the initial dielectric wave outside it, followed by 

 diffusion inwards, — I might be told that it was all " in Maxwell." 

 So it is ; but entirely latent. And there are many more things in 

 Maxwell which are not yet discovered.] This difference has been 

 the subject of a most moving appeal from Prof. Gr. F. Fitzgerald, 

 in ' Nature,' about three years since. There really seemed to be 

 substance in that appeal. For it is only a master-mind that can 

 adequately attack the great constructive problem of the sether, and 

 its true relation to matter ; and should there be reason to believe 



