414 C. A. Chant — Reception of Electric Waves. 



the length of the wire. The maxima are at 580 cms (the value 

 just given), and 1160 cms (=580x2), and a minimum at 850 cras , 

 half way between. 



Next, a large plate of metal, 90 by 180 cms , standing in a ver- 

 tical plane perpendicular to the wire, was securely joined to 

 one end of the wire, which w T as then examined as before. Here 

 with a capacity so large one would almost expect resonance to 

 take place with wires one-half the previous lengths. But such 

 was not the case, the chief resonance being with a length of 

 313 C1US , and less pronounced effects with lengths 190 and 502 cms 

 (Curve II). With a plate twice as large, however, the chief 

 resonance was with a wire 286 cms long. Next, a good earth 

 was obtained by soldering together metal sheets (total length 

 6'6 meters, width 80 cms ) and securely binding one end of the 

 strip so formed to a heating radiator. The maxima are given 

 in the table. When the earth was on the outer end of the 

 wire the chief maximum was given with a length of 300 cms , 

 when on the inner end a maximum was given with 280 cms . 

 The mean of these two values, 290 cms , is exactly half that 

 with the free wire.* This is evidence that on reflection at the 

 free end of a wire there is no loss of phase. 



On attaching the small cylindrical capacity supplied with 

 the instrument in place of the large plate, the curve III was 

 obtained, best resonance being given with a wire 500 cms long, a 

 smaller effect with 270 cms . Curve IY was obtained with the 

 same disposition as for curve I, but with antenna 3 meters 

 loner. 



It is seen that the cylinder capacity reduces the length of 

 wire from 580 to 500 ems , and thus it may be considered, in an 

 oscillating system, as approximately equivalent to 80 cms of the 

 wire. 



Curve V shows the resonance effect with the Slaby oscilla- 

 tor of antenna 3 meters. It shows resonance for a single half- 

 wave-length of 638 cms . 



In figure 6 are exhibited resonance effects obtained with the 

 simple Marconi radiator with antenna 3 meters long, the 

 receiving wire being at different distances and arranged in dif- 

 ferent ways. Curves I and II were taken with the receiving 

 wire 1 meter from the transmitting antenna, III to VI with 

 the distance 2 meters, and YII to X with it 3 meters. Curves 

 I, III, YI refer to a wire free at both ends ; II, IY, Y, YII, 

 IX with a large plate at the outer end ; and YI and X with 

 the plate at the inner end. In every case the plate stood in a 

 plane perpendicular to the wire. 



* In the former paper the experiments led to the conclusion that a large 

 capacity (e. g., the earth) joined to a vibrating system acts like a plane mir- 

 ror in optics, a result first predicted by J. von Geitler, Wied. Ann., lv, 

 p. 313, 1895. 



