﻿Magnetism and Static Electricity. 391 



idea the writer should have conveyed was that the pointed wire 

 and needle behaved as if they had polarity at their opposite ends 

 as regarded the electrifying body, and as if the polarity were so 

 distributed. During the time a pointed needle is being charged 

 the head is attracted, the point repelled from the electrifier; 

 but so soon as the tension of the electricity of the wire or needle 

 approaches that of the electrifying body the thick end is like- 

 wise repelled. 



The following experiment, which is the converse of the one 

 narrated, page 302, affords an additional illustration of this kind 

 of polarity ; at least that is the construction which the writer 

 puts on the phenomena presented. 



The magnet was arranged precisely as in the previous expe- 

 riment ; but the test-needle was brought over the other pole, so 

 that the head instead of the point of the needle was the attracted 

 end. Under these circumstances, when the system was charged, 

 the needle endeavoured to get still closer to the magnet, the 

 free end. being at the same time thrown more from the pole to 

 which it was before inclining. The needle was then placed at a 

 greater distance from the magnet : on charging the apparatus, 

 the attraction was very visible, the head being drawn towards 

 the magnet from a distance of an inch, and being so held whilst 

 the arrangement continued to be electrified. So soon, however, 

 as the positive and negative sides of the condenser were united, 

 the needle took up its former position in relation to the magnet. 



Touching the needle with a piece of copper wire during the 

 process of charging, or after the condensing arrangement was 

 charged, perceptibly increased the existing attraction of the 

 needle for the electrified magnet. 



The foregoing experiments were repeated with the horseshoe- 

 magnet as the negative side of the condensing system, the tin- 

 foil-covered glass being superposed as the positive side, the 

 whole being so arranged that the charged tinfoil should be be- 

 tween the poles of the magnet and the test-needle. 



Matters being thus arranged, on charging the apparatus as in 

 the previous experiments, the results afforded were in every way 

 precisely the same as when the magnet was the positively elec- 

 trified body in the system and had no dielectric between it and 

 the needles other than the air. 



Both repulsion and attraction of magnetized needles, under 

 the circumstances above described, are accompanied by a marked 

 divergence from the lines of magnetic force in which they would 

 have set if unbiased by static electricity. The distance of one 

 end of a magnetic needle from a magnet being made the same 

 under the influence of the magnetic force and the combined 

 forces, in the latter case the needle tends to put itself in a ver- 



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