Transmitting Antenna in Wireless Telegraphy. 7 



all secured during the investigation, especially in the space 

 between 100 and 300 cms from the free end. A possible cause 

 contributing to this may have been that the electrical disturb- 

 ance was not produced immediately at the earth end. 



In the second case the oscillating wire was free at each end, 

 and so the entire system of overtones was possible. The one 

 present, with half-wave-length of 282 cms , seems to be the fourth, 

 in this case the oscillator adding to the wire one-fourth of a 

 wave-length. 



It may be questioned why these particular overtones were 

 present, and the others not noticeable. I think it was because 

 the natural period of the oscillator alone was in approximate 

 accord with them, being about one-half that of those exhibited. 

 This would agree with the results of Lindemann,* who found 

 that the waves proper to the oscillator, as well as those of the 

 entire system of oscillator and wires, should be present. 



I have not been able to identify the other ripples of the 

 curves. 



Slabyf and Braun;); have both studied the simple Marconi 

 system. The former used a wire about 10 meters long, and 

 explored it with a spark micrometer in which a blunt metal 

 cone was opposed to a Hat face of arc carbon. According to the 

 curve he obtained (fig. 1 of his article), there was a standing 

 wave, with potential loops at the ends and a relative node in 

 the middle. In my experiments there is a node at the end of the 

 wire attached to the coil. Slaby concluded that the overtones 

 present were very trifling and that the oscillation emitted was 

 almost a pure fundamental. The fundamental is certainly 

 present in great intensity, but the readings giving it are some- 

 times scattering, as mentioned above, and the curve is not very 

 smooth. In some cases, too, as already seen, overtones show in 

 considerable strength. Slaby also found that when the pole of 

 the induction coil was joined, not to an end of the antenna but 

 to some other point, the oscillation produced showed consid- 

 erable distortion. This effect is similar to that noted above in 

 the case of the 1000 cms earthed wire. 



Braun used a wire 15 meters long stretched horizontally, 

 and from it suspended five small Geissler tubes, each with a 

 wire 50 cms long hanging below it. When the coil was in action 

 the tubes lighted up, but there was no trace of a node or a 

 ventral segment. 



*A. Lindemann, Ann. der Physik, ii, p. 376, 1900. 



f A. Slaby, Elektrotechnische Zeitschrift, 1902, p. 168; extended abstract 

 in Lond. Electrician, vol. xlix, p. 6, 1902. 

 X F. Braun, Phys. Zeitschrift, iii, p. 143, 1900. 



