1881.] 



Molecular Electro-Magnetic Induction. 



531 



6 complete permanent torsion (right-handed) negative 

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At this point the fibres of a soft wire commence to separate, and we 

 have no longer a complete single wire, but a helix of separate wires 

 upon a central structure. 



If now, instead of passing the current through the coil, I pass it 

 through the wire, and place the telephone upon the coil circuit, I find 

 that I obtain equally as strong tertiary currents upon the coil as in the 

 previous case, although in the first case there was produced longitudinal 

 electro-magnetism in the perpendicular wire by the action of the coil, 

 but in the latter case none or the most feeble electro-magnetism was 

 produced, yet in these two distinct cases we have a powerful current 

 produced not only upon its own wire, but upon the coil, thus proving 

 that the effects are equally produced both on the wire and coil. 



If we desire, however, in these reversible effects to produce in both 

 cases the same electromotive force, we must remember that the tertiary 

 current when reacting upon its own short wire produces a current of 

 great quantity, the coil one of comparative higher intensity. We can, 

 however, easily convert the great quantity of the wire into one of 

 higher tension by passing it through the primary of a small induction 

 coil whose resistance is not greater than one ohm. "We can then join 

 our telephone, which may be then one of a high resistance, to the 

 secondary of this induction coil, and by this means, and without 

 changing the resistance of the telephone, receive the same amount of 

 force, either from the iron wire or the coil. 



Finding that iron, steel, and all magnetic metals produce a current 

 by a slight twist, if now we replace this wire by one of copper or non- 

 magnetic metals we have no current whatever by an elastic twist, and 

 no effects, except when the wire itself is twisted spirally in helix, and 

 whatever current we may obtain from copper, &c, no matter if from 

 its being in spiral or from not being perpendicular to the axis of the 

 coils, the currents obtained will be invariably secondary and not 

 tertiary. If we replace the copper by an iron wire, and give it a 

 certain fixed torsion, not passing its limit of elasticity, we find that no 

 increase or decrease takes place by long action or time of being under 

 strain. Thus a wire which gave a sonometric force of 50° at the first 

 observation, remained perfectly constant for several days until it was 

 again brought to zero by taking off the strain it had received. Thus 

 we may consider that as long as the wire preserves its elasticity, exactly 

 in the same ratio will it preserve the molecular character of its 

 magnetism. 



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