Potential along a, Wire transmitting ElectrU 



are perhaps as good as one should expect with so dead-beat 

 an oscillator. 



From the results with the 10-cm. spheres the ratio of 



is 3*85, while with the 30-cm c 



The theoretical value given by 



Further exploration of the wire 



wave-length to diameter 

 spheres this ratio is 4*1*. 

 J. J. Thomson f is 3*6. 

 revealed no more minima. 



B. The Hertzian Oscillators. 



With the Hertzian oscillators the results were quite dif- 

 ferent from those just given, and indeed they differed con- 

 siderably amongst themselves. 



The tirst oscillator tried had sheet-zinc plates 40 cms. 

 square, with the straight wire between them 60 cms. long ; 

 and the wire transmitting the waves was 8()0 cms. long. One 

 minimum was very well marked, but there were no more 

 cle?ir ones. Then a second oscillator, with 20-cm. plates, and 

 otherwise of just half the size of the former was tried, but 

 the minimum, instead of being half the distance from the 

 end, was much farther from it. This led to the making of 

 additional oscillators, with plates 10, 15, 25, 30, 35, 50 cms. 

 square respectively, and with the wires between of propor- 

 tional length. Ttie spark-knohs were 19 mm. in diameter, 

 the same knobs being used with all the oscillators. 



Using these oscillators, readings were taken with wires 

 from 100 to 860 cms. long; and the results obtained are 

 exhibited in the accompanying table and curves. In the 

 table the positions of the minima are given by stating their 

 distances in centimetres from the free end of the wire. There 

 was always one more marked than the others, and this one, 

 indicated in the table by more prominent type, will be referred 

 to as the chief minimum. 



* It may be interesting to compare values of this ratio obtained by 

 other experimenters. Some are given in the following table, taken from 

 a paper by Hall in the ' Physical Review/ vol. v. p. 231, 1897 : — 



Diam. 

 in mm. 



X. 

 in mm. 



X/Diam. 



Experimenter. 



80 



200 



2 50 



Righi 



37-5 



106 



2-83 





8 



26 



3-25 





7-8 



184 



2-36 



13ose 



198 



91 



4-71 



Hull 



93 



43 



4(>2 





7-9 



40 



.VIS 



., 



-j- J. J. Thomson, ' Recent Researches/ p. .'570. 



