along Wires and their Reflexion at the Oscillator. 151 



It may be interesting to regard, in the light of the results 

 in the second table, two sets of observations taken by the writer 

 in Bonn during the summer of 1893 while working under 

 the late Professor Hertz*. In the course of those experi- 

 ments (directed primarily to an object quite different from 

 that now under discussion) the electrometer was placed almost 

 at the end of the line. By an entirely different method from 

 that now adopted, ratios were obtained for the electrometer- 

 throws due (1) to the passage past it of the sum to infinity of 

 the geometrical progressions formed by the outward and 

 return waves, and that due (2) to the single passage of the 

 initial wave-train. The lengths of the line to the electro- 

 meter in the two cases were 160 and 91*5 m. respectively, 

 and the corresponding ratios were 1 : 0'34 and 1 : 0*31. 

 Hence for this case equation (4) takes the form 



p 2 re- il °=r-2, (5) 



since / 2 = 0. 



Solving simultaneously the two equations thus derived from 

 the experimental values of r, we obtain 



6-=O00027, p 2 =0*476,l , a . 



o- = 0-0000062 and p^O-69 J " ■ • • vV 



In these experiments the primary oscillator as regards the 

 parts SPGP'S' (fig. 1) was precisely the same as in the 

 present paper, and it seems noteworthy that its reflexion 

 coefficient is practically the same. The values of the resistance 

 and inductance of the secondary circuit of the induction-coil 

 used in Bonn cannot be stated, as they were not at the time 

 regarded as of any material consequence and accordingly 

 were not measured. 



It will be seen that the attenuation constant in the 1893 

 case is about half that in the present work. This may possibly 

 be due to the wood separators used along the line being much 

 drier in a German summer than in an English winter and 

 spring. 



Comparisons with Heaviside' s long-wave theory of reflexion. — 

 After obtaining experimentally the unexpected result that of 

 the wave energy incident upon the primary oscillator only 

 about one-half or less was reflected along the line, it seemed 

 incumbent on one to test this if possible by theory. And in 

 this connexion I have pleasure in acknowledging my 

 indebtedness to Mr. Oliver Heaviside for an explanation of his 



* Proc. Roy. Soc. vol. lvii. pp. 72 & 75 (1895) ; D.Sc. Thesis for the 

 University of London, 1894, pp. 20-22 and 28-29 ; Wied. Ann. Bd. liii, 

 pp. 525-627 and 528-529 (1894). 



