338 Mr. C. A. Chant on the Variation of 



A and B and B and C, and the oscillations on the sphere 

 were transmitted to the wire across the mica plate, m. 



The wires used were quite short, ranging from 1 metre to 

 S'6 metres in length. 



III. Results of Experiments. 



It will be convenient to divide the results into two parts : — 

 A ? those obtained with the oscillators a, b, c of fig. 1 : and 

 B, those with the Hertzian oscillators. 



A. Cylindrical Oscillator (fig. 1, a). 



In PI. VII. fig. 7, a, b, c are shown curves obtained with the 

 cylindrical oscillator, which was made of sheet platinum on a 

 wooden form with well- shaped hemispherical ends. Here, 

 as always, the greatest variation in potential was at the end 

 of the wire. It gradually fell until a minimum was reached 

 at approximately 20 cms. from the end, and after another 

 rise it dropped again to a minimum at approximately 60 cms. 

 Each of the last two curves gives a half-wave-length of 

 10 ems., the first one 38 cms., or a mean wave-length for the 

 oscillator of approximately 79 cms. 



In every instance the actual readings are shown. 



Linear Oscillator (fig. 1, c) 



Curves obtained with this oscillator are shown in PI. VII. 

 fio\ 7, d, e. Curve (d) is the mean of two sets of readings with 

 five swings of the pendulum. The mean of five sets, each of 

 two swings, gave the same minima, though the curve was 

 not so good. Curve (e) is a repetition of the second portion 

 of the readings : it is the mean of two sets of five swings each. 



Here three minima are easily seen at 19, 59. and 99 cms. 

 respectively, from the end ; and the wave-length is thus 

 approximately 80 cms. 



Spherical Doublet (fig. 1, b). 



Curves for this oscillator are given in PL VII. fig. 8. It was 

 much more difficult to get consistent series of readings with it. 

 Curves (a) and (b) are for the 10-cm. spheres. The half- 

 wave-lenuths deduced are respectively 19 and 19*5 cms., with 

 a mean wave-length of oS'D cms. Curves [c) and (d) are for 

 the 30-cm. spheres. The half-wave-lengths from these are 

 61 and 62 cms. respectively, with a mean wave-length of 

 123 cms. 



These curves are not as smooth as the former ones, but 



