62 



On Sequences of Reversals. 



will be an action arising from the tension of the lines of force 

 tending to draw all the axes towards the mean direction of the 

 magnetism ; and thus the length of the path, and consequently 

 the resistance, will be diminished as the magnetism increases. 

 This has all been worked out in detail and shown to be capable 

 of representing the facts minutely, in the papers referred to. 

 All I want to show here is that we can refer our results as to 

 increase or diminution of resistance by sequences of reversals 

 to this theory. For the permeability would be diminished by 

 partially filling up the saturation-capacity, and increased by 

 partially fixing the molecules in positions of diminished resist- 

 ance. All magnetization tends to retain the latter change in 

 the same direction ; i. e. to diminish the mean inclination of 

 the axes, and consequently the resistance. But successive 

 reversals of diminishing currents are capable of removing the 

 greater part of the magnetism that sticks in the particles 

 (subpermanent magnetism). This accounts generally for the 

 observation that immediately after saturation the resistance is 

 increased, but when a descending sequence of reversals is in- 

 terposed the resistance is diminished. For the large residual 

 charge after saturation diminishes the permeability to an ex- 

 tent exceeding the effect of inclination of axes. But when 

 the residual charge is dispersed by the reversals of a descend- 

 ing sequence, the effect of the diminished inclination of the 

 axes remains, and increases the initial permeability. 



The figure and Tables which follow exhibit the results of 

 the experiments in question. 



Soft-Iron Bar *938 centim. radius, 

 28*55 centim. length. 



A. 



B. 



C 



. 



Original ascending 



Second ascending 



Descending sequence. 



sequence. 



sequence. 







33, 



P- 



33. 



P- 



33. 



P- 





centim. 





centim. 





centim. 



25 



•343 



14 



•356 



15 



•328 



168 



•315 



106 



•342 



237 



•289 



414 



•272 



258 



•314 



978 



•254 



1,423 



•237 



276 



•305 



2,529 



•250 



2,467 



•238 



384 



•286 



5,577 



•246 



10,210 



•233 



1,244 



•257 







17,214 



•299 



4,384 



•231 







17,858 



•331 



19,396 



•385 







19,289 



•445 











19,650 



•552 











