of Electric Waves through Wires, 125 



We can moreover give further proofs, which are more con- 

 vincing. We may prevent the wave returning from 8 to A 

 from dissipating its energy in sparks, by making the spark- 

 gap either vanishingly small or very great. In this case the 

 wave will be reflected at A, and will now return again from 

 A towards 8. In doing so, it must meet the direct waves 

 from 8 to A and combine with them to form stationary waves, 

 thus giving rise to nodes and ventral segments. If we suc- 

 ceed in proving their existence, there will be no longer any 

 doubt as to the truth of our theory. For this proof we must 

 give somewhat different dimensions to our apparatus in order 

 to be able to introduce electric resonators into its interior. I 

 therefore led the central wire through the axis of a cylindrical 

 tube 5 metres long and 30 centim. diameter. It was not con- 

 structed of solid metal, but of 24 wires arranged parallel to 

 each other along the generating surface, and resting on seven 

 equidistant and circular rings of strong wire, as shown in 

 fig. 2. I made the requisite resonator in the following 

 manner : — A closely-wound spiral of 1 centim. diameter was 



Fig. 2. 



formed from copper wire of 1 millim. thickness ; about 125 

 turns of this spiral were taken, drawn out a little, and bent 

 into a circle of 12 centim. diameter; between the free ends 

 an adjustable spark-gap was inserted. Previous experiments 

 had shown that this circle responded to waves 3 metres long 

 in the wire, and yet it was small enough in size to admit of its 

 insertion between the central wire and the surface of the tube. 

 If now both ends of the tube were open, and the resonator 

 was then held in the interior in such a way that its plane 

 included the central wire, and its spark-gap was not directed 

 exactly inwards or outwards, but was turned towards one end 

 or the other of the tube, brilliant sparks of ^ to 1 millim. 

 length were observed. On now closing both ends of the tube 

 by four wires arranged crosswise and connected with the cen- 

 tral conductor, not the slightest ' sparking remained in the 

 interior, a proof that the network of the tube is a sufficiently 

 good screen for our experiments. The end of the tube on the 

 side /3, that, namely, which was furthest away from the origin 

 of the waves, was now removed. In the immediate neigh- 

 bourhood of the closed end, that is at the point a which corre- 

 sponds to the spark-gap A of our previous experiments, there 

 were now no sparks observable in the resonator. Bui on 

 Phil. Mag. S. 5. Vol. 28. No. 171. August 1889. L 



