702 THE AMPERIAN CURRENTS. 



other words, the small current round one molecule may 

 be parallel to that round another, at right angles to 

 that round a third molecule, and so on, so that there 

 are on the average as many currents in one direction as 

 there are in any other. The obvious consequence of 

 this is that the total action of all these currents upon any 

 external substance is nothing, because the effect which 

 might be produced by one set of currents having a 

 given direction is precisely neutralised by another set 

 flowing in the opposite direction. Further, it is assumed 

 that the position of these small circuits is by no means 

 fixed, but that under the influence of a strong current 

 which flows near them they may take up new positions. 

 Now the action of a fixed current upon a movable one 

 is, in accordance with Ampere's laws, to make both cur- 

 rents parallel and their directions the same. The same 

 action must be produced in a system of movable mole- 

 cular currents by a galvanic current in their vicinity. 

 Each successive coil of the spiral through which it passes 

 represents nearly a circular closed current, and gives 

 to the molecular currents in its neighbourhood a position 

 parallel to itself and a direction like its own. But 

 currents which are parallel and in the same direction 

 attract one another; hence the bar is attracted by the 

 spiral, and drawn into the interior of the latter as far 

 as possible. Moreover, as soon as the molecular currents 

 have changed, their irregular positions to one of paral- 

 lelism, they are capable of acting exactly like the 

 system of parallel currents in the spiral, that is, they 

 are capable of causing the molecular currents in another 

 piece of iron to become parallel and assume a like 

 direction; there will thus be mutual attraction produced 



