Belas and Hartog — Path of a Small Permeable Body, <Sfc. 39 



certain stage the sole, freed from this coercive force, would suddenly reverse, 

 and we would now be working in a highly complex field, viz., (i) the earth's 

 horizontal component ; (ii) the field of the electro-magnet parallel indeed 

 to this ; (hi) the sub-permanent field of the sole, whose poles might be any- 

 where in it. We took off the sole, had it heated red-hot and cooled all 

 night in cinders lying east and west ; but even this failed to quite remove the 

 permanent magnetism, although the curves were somewhat amended. We 

 now abandoned the base-plate, supported the magnet poles on a wooden base, 

 and removed then to a small room set apart for magnet work, being free 

 from iron fixtures. 



v^v.-:-./.-:- 



• "-* '" ! • i • 



■.■::■■•:■■: N 



Fig. 4. 



On repeating our work, there seemed at first to be a marked improvement, 

 but sooner or later a curve would be traced which would cross some of the 

 previous ones, and the stage at which this interesting event would take 

 place could not be foretold. 



It seemed to us that though we had no permanent magnetism cropping 

 up as before, yet as the two cores of the magnet were unlikely to be exactly 

 alike in hardness, we were dealing with two separate magnets of unequal 

 strength, and moreover, the ampere-turns on each were not likely to be 

 exactly the same ; the case was even worse than before ; so we returned to 

 the base-plate, taking care that its permanent magnetism was in the same 



