PERIODS OF ELECTRICAL VIBRATIONS. 199 
mental evidence had lately been published,’ whichapparently 
accorded with such a view. The well known experiments . 
of Sarasin and De la Rive and others, however, make the 
wave length greater than twice the length of the resonator. 
It seemed essential therefore, to strengthen if possible, the 
experimental position, and with this object in view the 
present experiments were undertaken. Since their prac- 
tical completion, theoretical support has been withdrawn 
from the results first mentioned, by the publication of 
Macdonald’s Adams Prize Essay on Hlectric Waves, (Cam- 
bridge 1902) which has wholly changed the theoretical 
aspect. Macdonald’s calculations so closely agree with 
the bulk of the experimental results that there can no 
longer be any doubt that the wave length of the free oscil- 
lation connected with open circuits is considerably greater 
than twice the length of the wire. 
GENERAL RESULTS. 
Open circuits.—A. Slaby’ has investigated, with a spark 
micrometer, the potential at various points of a straight 
wire when electrical vibrations take place along it. He 
finds a stationary wave with potential loops at the ends 
and a relative node atthe middle. Such an experiment does 
not seem calculated to determine the actual wave length of 
the vibration connected with the wire, but apparently Dr. 
Slaby is satisfied from a consideration of the observations 
that the wave length of the oscillation is equal to twice 
the length ofthe wire. He has also theoretically discussed 
the problem and “the calculation gives a full confirmation 
of the experimental results.’’ The experiments were made 
with wires from one to ten metres long. 
* Turpain—Jour de Phys. 10, p. 425, 1901. Slaby, Electrotech. Zeit. 9, 
p. 165, 1902. 
? Slaby—Electrotech. Zeit. No. 9, p. 165, 1902. 
