60 Chant — Variation of Potential along a 



Thus, to examine any portion of the wire, the carriage was 

 moved along to the required place, the distance of which from 

 the end of the wire was measured by a scale on the ways on 

 which the carriage moved. The detector was magnetized, 

 then placed in its pocket beside the glass tube, and sparks 

 made to pass at the oscillator for a certain length of time. The 

 detector was then removed and examined by the magnetome- 

 ter. This process was systematically carried out, beginning at 

 the end of the wire and advancing by equal spaces. 

 5 



For the linear oscillator, shown in fig. 1, c, the arrangement 

 was precisely the same as for the cylinders. For the Hertzian 

 oscillators, fig. 1, d, a rounded end was given to one of the 

 plates by taking a piece of brass rod 6 mm in diameter and about 

 2cms l on g ? rounding the ends, and then making a slit in one 

 end, which allowed it to be slipped over the plate. This is 

 shown in fig. 5. 



The arrangement for the spherical doublet is shown in fig. 6. 

 When the coil was in action sparks passed between A and B 

 and B and C, and the oscillations on the sphere C were trans- 

 mitted to the wire across the mica plate, m. 



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

 8 # 6 meters 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 lig. 1 ; and B, 

 those with the Hertzian oscillators. 



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

 In fig. 7, a, b, g, are shown curves obtained with the cylin- 

 drical 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 approxi- 

 mately 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 40 cms , the first one 38 cms , 

 or a mean wave-length for the oscillator of approximately 79 cms . 



