Potential along a Wire transmitting Electric Waves. 335 



investigation* in which the magnetic detector was used, the 

 fact that an electrical disturbance about a wire parallel to the 

 wings of the detector exerted a strong action on the detector 

 was continuously and painfully evident. Indeed, the effect 

 arising from the connecting wires at first entirely masked the 

 true radiation from the oscillator. 



This suggested the possibility of conveniently exploring 

 the held along a wire by shortening the wings of the detector 

 and then placing it close to the wire at various points in its 

 length. The experiment was tried, but the demagnetization 

 of the detector was small. However, on removing one wing 

 and placing the other near the wire the effect was much 

 greater and easily measurable. 



But the action with one wing is not at all the same as with 

 two. When the detector with two wings is placed along the 

 wire, the surging in its helix and the consequent demagneti- 

 zation is greatest at points where the current oscillati m is 

 greatest, i. e. at a current loop ; the effect is least at a current 

 node. With a single wing these results are exactly reversed, 

 the effect is greatest at a current node, which is, of course, a 

 potential loop. This can be explained in the following way : — 

 The little wing and the portion of the wire just beside it act 

 as a miniature condenser, and when there is a maximum 

 variation of potential in the element of wire there will also 

 be a maximum variation in the detector wing, which will 

 cause currents to surge back and forth in the helix, and so to 

 demagnetize the iron core. At a current loop (or potential 

 nodej the variation in potential is a minimum, and so the 

 detector when placed there will show minimum demagneti- 

 zation. Indeed, the indications of the magnetic detector 

 should be precisely similar to those of the bolometer as used 

 by Rubens. 



An attempt was then made to force standing waves in a 

 wire, and preliminary experiments seemed to show the possi- 

 bility of determining the wave-lengths of oscillators in this 

 way. Some measurements were made then, which, since the 

 writer's return to Toronto, have been considerably extended. 



Fig. 1. 



fe 00° e =^^=- CH^ 



& b c d 



The oscillators were of four kinds, illustrated in tig. 1. 

 * C. A. Chant, 'An Experimental Investigation into the "Skin"- 

 effect in Electrical Oscillators/ Am. Journ. Sci. xih. p. 1 (1002) : Phil. 

 Mag. [6] vol. hi. p. 425 (1902). 



