Lifting Power of the Electro-Magnet. 311 



current be passed, it destroys this condition, unless very feeble, but even then 

 it lessens it ; thus 0"0127 reduces A from 12941 to 117'51. I may add, that 

 even the fifteenth of this will excite this magnet, and change its residual 

 magnetism. 



While the magnet is thus circumstanced, it shows faint traces of free mag- 

 netism ; each cylinder having its accustomed polarity at its acting surface, the 

 opposite at its other extremity, and a neutral point in the middle. The ends 

 of the keeper and base have the same polarities as those of the cylinders with 

 which they are in contact. If one cylinder only be excited, the value of A is 

 the same as for the two, but the distribution of the magnetism is modified, as 

 might be expected. 



