WAVEGUIDE TRANSMISSION 297 



should be released on the interior wall of a closed metal cylinder. This 

 problem is even now of considerable interest in connection with resonance 

 in hollow metal chambers. The following year Joseph Larmor examined as 

 a special case of electrical vibrations in condensing systems the particular 

 waves that might be generated by spark-gap oscillators located in hollow 

 metal cylinders. A more complete analysis relating particularly to propaga- 

 tion through dielectrically-fiUed pipes both of circular and rectangular cross 

 section was published in 1897 by Lord Rayleigh. Later (1905) Kalahne 

 examined mathematically the possibility of oscillations in "ring-shaped" 

 metal tubes. Still later (1910) Hondros and Debye examined mathematically 

 the more complicated problem of propagation through dielectric wires. Trans- 

 mission through hollow metal pipes was also considered by Dr. L. Silberstein 

 in 1915. 



As regards experimental verification, it is of interest that Sir Oliver Lodge 

 as early as 1894 approached but probably did not quite realize actual wave- 

 guide transmission. In a demonstration lecture on electric waves given before 

 the Royal Society, he used, as a source of waves, a spark oscillator mounted 

 inside a "hat-shaped" cylinder. An illustration pubHshed later suggests that 

 the length of the cylinder was only slightly greater than its diameter. There 

 is no very definite evidence that the short cylinder functioned as a waveguide 

 or that such a function was discussed in the lecture. Perhaps of greater 

 significance were some experiments reported a year later by Viktor von Lang 

 who used pipes of appreciable length and repeated for electric waves the 

 interference experiment that had been performed for acoustic waves by 

 Quincke some years earlier. Other similar experiments were later performed 

 by Drude and by Weber. 



About 1913 Professor Zahn of the University of Kiel became interested 

 in this problem and assigned certain of its aspects to two young candidates 

 for the doctorate, Schriever and Renter by name. They had barely started 

 when World War I broke out, and both left for the front. Zahn continued 

 this work until he was called a year later. It is reported that by this time he 

 had succeeded in propagating waves through cylinders of dielectric, but it 

 is understood that he did little or no quantitative work. Renter was killed 

 at Champagne in the autumn of 1915, but Schriever survived and returned 

 to complete his thesis in 1920, using for his source the newly available 

 Barkhausen oscillator. 



The contributions of Thomson, Rayleigh, Hondros and Debye, and 

 Silberstein were, of course, purely m.athematical. Those of von Lang, Weber, 

 Zahn and Schriever were experimental, but they were of rather limited 

 scope. The concept of the hollow pipe as a useful transmission element, for 

 example as a radiator or as a resonant circuit, apparently did not exist at 

 these early dates. Nothing was yet known quantitatively about attenuation, 



