XXIV.—ON THE POSSIBILITY OF ORIGINATING WAVE DISTURB- 
ANCES IN THE ETHER BY MEANS OF ELECTRIC FORCES :— 
CORRECTIONS AND ADDITIONS. By Geo. Fras. FirzGera.p, M.A., F.T.C.D. 
Read May 5th, 1882. 
y 
Since publishing Part II. of these papers (these Transactions antea, page 173), 
I have come across an investigation of the differential equation I there studied 
in Lord Rayleigh’s “ Theory of Sound,” Vol. IL., § 276. He assumes the solution to 
contain imaginary terms of the form e™, just as I assumed it to contain real terms 
of the form cos nt and he obtains the same general form of solution as Ido. Toa 
simply periodic term, however, there corresponds in his solution a term of the form— 
4 COS (nt—mr) 
iP 
instead of the term I obtained, 
cos nt cos mr 
- 
Taking Lord Rayleigh’s form of solution would lead to the conclusion that a 
simply periodic current would originate wave disturbances such as light and not 
the stationary waves that my solution leads to. 
I have not been able from purely mathematical considerations to determine which 
form of solution is preferable. Each is only a partial and not a general solution, 
and the form depends on the limiting conditions which are the same in both, when 
ris small and when it is infinite. When mr is small, the two forms are indistin- 
guishable, and it is not easy to make experiments in which mr is not small, and I 
know of none that can help to decide between the forms. If we could make 
A. 
experiments where (™=5) we could easily distinguish between them, but as 
this would be at a distance of several miles from the varying current when the 
variations were as rapid as in the highest audible note, there does not seem much 
hope from experiments in this direction. Dr. Oliver Lodge has already tried to 
originate light by induced currents of a high order. It does not seem that this 
method of producing very rapidly varying currents would succeed beyond the third 
or fourth orders, for the induced currents of the higher orders tend more and more 
to become simply periodic, and after that there is only one induced current corres- 
ponding to each inducing one. It might, however, be possible to obtain sufficiently 
rapidly alternating currents by discharging condensers through circuits of small 
