Intelligence and Miscellaneous Articles. 239 



duced in the coils of the spiral is in the same direction as that of the 

 rotating clamp^that is, in the direction of the torsion, and this 

 -whatever the direction of the rotation. On untwisting the wire 

 there is an induced current in the opposite direction. If the direc- 

 tion of the current passed through the wire he reversed, the direction 

 of the currents produced by torsion and detorsion is changed also. 



If even after opening the current the wire is twisted and untwisted, 

 induction-currents occur in the surrounding spiral which have the 

 same direction as the induction-currents on twisting and untwisting 

 the wire during the passage of the current. 



By the assumption of rotating molecular magnets these phenomena 

 may be sufficiently explained. If a current is passed, for instance, 

 from the rotating to the fixed clamp, the molecular magnets arrange 

 themselves in such a manner that their north poles are turned towards 

 the left of a man swimming in the current on the axis of the vvire, 

 and even after the cessation of the current they retain this position. 

 If now the wire is twisted in the direction of the hands of a watch, 

 for instance, for an observer standing in front of the clamp, according 

 to earlier observations the molecular magnets will turn their south 

 poles to the posterior end of the wire at the clamp, by which the 

 wire also acquires a south pole. Hence an induction-current must 

 be formed in the induction-spiral, which would impart to the wire an 

 opposite polarity, and must traverse the wire therefore in the same 

 direction as that in which the rotation of the clamp has taken place; 

 in untwisting, the molecular magnets return to their original posi- 

 tion, and a current in the opposite direction is produced, which would 

 of itself prevent them from doing this. Inverting the direction of 

 the current passed through the wire, or of the torsion, an ignited 

 wire was clamped, as before, in the torsion- apparatus, and a galvanic 

 current passed through it. After opening the latter, the fixed and 

 the rotating clamp between which the wire was stretched were con- 

 nected with the multiplier of a mirror galvanometer. If the wire 

 was now twisted either in one direction or the other, the deviation 

 of the magnetic mirror again indicated the occurrence of induction- 

 currents. The direction of these currents is always the same as the 

 direction of the current previously passed through the wire, whatever 

 be the direction of the torsion. Hence in a certain sense the cur- 

 rent which had been passed through the wire occurred again on 

 twisting. If now the wire was untwisted, a new induction-current 

 was formed in the opposite direction. 



The formation of these induction-currents also can be deduced 

 without difficulty. By the current which is passed through the iron 

 wire its molecular magnets are placed transversely, with their axes 

 at right angles to the axis of the wire. If now the wire is twisted, 

 ..the molecular magnets are deflected on one side or the other from 

 their transversal position, and at the same time an induction-current 

 must be formed which of itself would bring them back into that po- 

 sition — that is, having the same direction as the current previously 

 passed through the wire. As, on untwisting, the molecular magnets 



