associated with thin terminated Conducting Rods. 277 
not be sufficient, does not appear to meet the case, as ex- 
periment would seem to show that the phenomena are the 
same whatever the material of the wire may be, and that 
only the distance of the last node is abnormal. Theoretically 
it is of course beyond doubt, and all experiment confirms the 
conclusion, that the circumstances of propagation of electric 
waves of high frequency along a wire are independent of the 
magnitude or form of its cross section ; the sheet of intense 
disturbance around the wire is thin, the direction of propa- 
gation is along its surface, and the velocity of propagation, 
therefore, that of radiation in the surrounding medium. 
The only difficulty is in the treatment of a free end. 
According to the ellipsoidal analysis referred to by Lord 
Rayleigh, the wave is simply reflected at the free end without 
sensible loss by radiation, the free end being a true electric 
loop. Such modes of free vibration in terminated wires, if 
theoretically possible, are thus largely isolated, and have very 
slight connexion with the surrounding medium. Conversely, 
they ought to be correspondingly different to excite waves 
transmitted across this medium; and it appears open to some 
question whether they are sensibly excited at all. 
The facts seem to be as follows: If a wire is bent round 
into a resonator with the ends close together, the radiation 
from these two adjacent ends is of the same type as that from 
a Hertzian oscillator, but the rate of decay of the oscillations 
is very small. If the wire is partially straightened out, the 
vibrations are rapidly damped, but in a way not affected by 
further change of form: there must in consequence be 
powerful radiation from the ends. Observation, with Mar- 
coni’s antenne for example, corroborates this view, that wires 
carrying waves emit powerful radiation which must come 
mainly from their free ends. 
This facility of egress of radiant energy from a free end 
seemed to me to be the essential feature of the problem of 
the electrical oscillations associated with a terminated straight 
wire. The difficulty hes in deciding what the circumstances 
of the radiation from a free end are, the character of the 
disturbance around the end being no longer so obvious as in 
the case of the resonator. 
An important difference between the view supported by 
Lord Rayleigh and that which regards the effect of the free 
ends as the essential feature, is that on the former view the 
damping of free vibrations on a terminated straight wire 
would not be very rapid, whereas on the latter it would. 
Now experiment would seem to show that such vibrations 
