March, 1918] A Lecher System — Experimental 157 



VII. How Does the Capacity of the Coxuexsers Vary 

 With the Edge-on Distance Between Plates 

 AND With the Plate Thickness? 



Blake and Sheard found that for small values of y the value 

 of ho, K, that is, the end-capacity expressed in equivalent wire- 

 length, was practically constant, as calculated from the data for 

 the different harmonics. This was to be expected on account 

 of the small range of frequencies they worked with, viz., 1 to 9. 

 The range in this paper is but slightly greater, viz., 1 to 11, 

 hence we should expect to confirm their results in this regard. 

 This is indeed the case as Table I clearly shows. Columns 5 

 to 10 inclusive give the mean positions of all the peaks for all 

 the tones. The upper set of figures in columns 11 to 16 inclusive 

 give the experimental values of Xs, the wave-length correspond- 

 ing to the frequency number, s. In column 13 the figures in 

 parentheses are the observed values of the wave-lengths of the 

 fifths obtained by subtracting the two outer fifths from each 



other and dividing by 2, e. g. 2 36.12—63.88 ^^^-^2. Blake and 



Sheard observed that the outer internodal spaces for the fifths 

 were distinctly larger than for the inner internodal spaces. 

 Since they did not observe this for the sevenths and ninths 

 within the limits of experimental error they attributed this to 

 the presence of the small ebonite supports, Ri, Ro, R3, R4 in the 

 immediate vicinity of these outer peaks for the fifths. Our 

 results confirm theirs. In the calculations the outer fifths were 

 not used. We found, however, that the intensity of the outer 

 fifth near the oscillator is not as great as that of either of the 

 two inner fifths, whereas it should be somewhat greater. This 

 was true for all the values of y for which the outer fifths were 

 measured. Column 17 gives the position C, Figure 1, obtained 

 by adding 3.5H-1/2 (y — 2) to the plum-bob reading M as given 

 on the 3-meter stick. It is the reading of the back of the 

 Lecher plates next to the receiver. Column 19 is calculated in 



