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LONDON, EDINBURGH, ayp DUBLIN 
PHILOSOPHICAL MAGAZINE 
AND 
JOURNAL OF SCIENCE. 
[SIXTH SERIES) 
| 
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OCTOBER 19064, “6 
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XLII. The Propagation of Electric Waves along Spira Wires, 
and onan Appliance for Measuring the Length of Waves 
used in Wireless Teleqraphy. By J. A. Frimene, 11.A., 
D.Sc. F.R.S., Professor of Electrical Engineering in 
University College, London”. 
3 [Plate XTIL.] 
ss a propagation of electric waves along wires having 
helical form has engaged the attention of several 
physicists, but there are points of interest in connexion 
with it not entirely exhausted. Hertz has described an 
experiment in which he established stationary electric waves 
on a spiral wire, and compared the distance of the nodes with 
the corresponding distances when the wire was stretched out 
straight +. He found the internodal distances for the same 
frequency much smaller in the former case, and he suggests 
that Maxwell’s theory is unable to account for this diminished 
velocity along the spiral conductor, as compared with that 
along a straight one. | 
G. Seibt devised apparatus for showing experimentally 
the production of stationary electric waves on helices of 
insulated wire, but his theory of the apparatus was not tested 
by quantitative experiments or measurements {. 
* Communicated by the Author, having been read at the meeting of 
the British Association at Cambridge, 1904. 
+ See ‘Electric Waves,” H. Hertz. English Translation by D. L. 
Jones, pp. 158, 159. 
{ “Hlektrische Drahtwellen,” G. Seibt, Elektrotechnische Zeitschrift, 
vol. xxii. April 10, 17, 24, May 1, 8, 1902. : 
Phil. Mag. 8. 6. Vol. 8. No. 46. Oct. 1904. 2G 
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