R. S. HYER MEASUREMENTS OF ELECTRIC WAVES. 
59 
Hertz. According to his view, such a difference would be caused by a 
difference in the size of the oscillator, hut in no other way. The one used 
in my experiment was exactly similar and of the same dimensions as 
the one employed by him. I soon discovered that this difference was due 
to the difference in the size of the resonators, and likewise discovered that 
the differences in the nodal points were proportional to the differences in 
the size of the resonators. At that time I was not aware of the fact that 
a similar discovery had already been made by Sarasin and De La Rive at 
Geneva. It is now well known that they found the nodal distances in 
both air and wires to depend solely upon the length oif wire in the reso- 
nator, and stated that this distance was always four times the radius of the 
circle employed, or 20 per cent greater than the length of wire in the 
resonator. In view of this discovery, Prof. J. J. Thomson has well said 
that if we are to retain Hertz’s explanation of the formation of these 
nodal points, we shall have to suppose that the oscillations of the vibrator 
are very complex, constituting, as it were, a continuous electrical spec- 
trum. If we adopt such a view, how can we determine the period of any 
particular set of vibrations? Without such a determination, the Hertzian 
method of calculating the velocity of propagation fails entirely. 
A much simpler view than that of a continuous spectrum is offered by 
Thomson. He regards the oscillations of the vibrator as being practically 
dead-beat; and therefore, incapable of making any standing waves by 
reflection. The so-called nodal points are explained as being interference 
phenomena in the resonator itself, and not in the air. The dead-beat dis- 
turbance originating in the oscillator, moving with a finite velocity, falls 
upon the resonator and produces in it a disturbance that is quite pro- 
tracted. The exciting wave travels on to the reflector and is thrown 
back upon the resonator. This second impact will interfere with the 
excitement produced by the first, intensifying or diminishing it according 
to their difference in phase. If .we assume, as was shown by the fact 
that these nodal distances in wires and in air are the same, that the ex- 
citing agent travels in the air with the same velocity as that of the dis- 
turbance in the wire, we may expect to find at certain definite distances 
from the reflecting screen points where the first disturbance is intensified 
by the reflected impact, and, equidistant between these, other points 
where there is a neutralization. The theory of electric oscillations, as 
worked out by Thomson, would lead us to anticipate a practically dead- 
beat oscillation in such an apparatus as was employed by Hertz, and an 
assumption that such is their real nature very satisfactorily explains all 
the phenomena observed by him, and also the subsequent observations 
reported by Sarasin and De La Rive. To this statement one important 
exception must be made. This was clearly recognized by Thomson, and 
