PERIODS OF ELECTRICAL VIBRATIONS. 205 
affected by the diameter of the wire of which the resonators 
are made. 
Closed rings.—Kiebitz* has shown how a filings coherer 
may be used to determine the existence of electrical reson- 
ance. In one set of experiments the coherer was placed 
across a gap in a circular resonator. The oscillator was a 
straight wire 77 cms. long. It is stated as the result of these 
trials, that with such a resonator there is the best response 
when its length is equal to the wave length of the radiation 
falling on it. Thisis asserting alittle too much. The only 
statement justified by the experiments, on this point, is that 
the resonator gives the best response when its length is 
double that of the straight wire oscillator. 
Kiebitz’s resonator must be considered a completely 
closed ring, and his experiment proves the possibility of 
inducing oscillations in connection with sucha circuit. The 
present experiments givea result not differing greatly from 
that just stated. 
Turpain* from experiments with the resonator enclosed 
in an exhausted glass tube says :—‘‘If one completely closes 
the gap, no current circulates in the closed circuit which 
the resonator presents. The electric density is zero at 
every point of the circuit at each instant.’’ In view of 
Kiebitz’s experiment this statement must be considered 
inaccurate. 
The results of the present experiments on closed rings 
may be stated as follows :—Taking as astandard the period 
oi the electrical vibration associated with a narrow rect- 
angular closed circuit, where the longer side of the rectangle 
is parallel to the direction of propagation of the waves, an 
elliptical closed circuit of very small eccentricity, with its 
major axis parallel to the same direction, may be considered 
‘ Kiebitz—Ann. der Physik., vi., 4, p. 741, 1901. 
* Turpain—Journ. de Phys. x., p. 434, 1901. 
