supposed Polarity of Diamagnetic Bodies. 95 



consequently none at the galvanometer ; but when the ends 

 were soldered together, the needle was well affected. In the 

 first condition, the currents, which tended to he formed in the 

 mass of moving metal, could not exist because the metal cir- 

 cuit was interrupted ; in the second they could, because the 

 circuit was not interrupted; and such division as remained 

 did not interfere to prevent the currents. 



2661. The same results were obtained with other metals. 

 A core cylinder of gold, made of half-sovereigns, was very 

 powerful in its effect on the galvanometer. A cylinder of 

 silver, made of sixpenny pieces, was very effectual ; but a 

 cylinder made of precipitated silver, pressed into a glass tube 

 as closely as possible, gave no indications of action whatever. 

 The same results were obtained with disc cylinders of tin and 

 lead, the effects being proportionate to the condition of tin 

 and lead as bad conductors (2655.). 



2662. When iron was divided, the effects were exactly the 

 reverse in kind. It was necessary to use a much coarser gal- 

 vanometer and apparatus for the purpose ; but that being done, 

 the employment of a solid iron core, and of another of the 

 same size or weight formed of lengths of fine iron wire (2659.), 

 showed that the division bad occasioned no inferiority in the 

 latter. The excellent experimental researches of Dove* on the 

 electricity of induction, will show that this ought to be the case. 



26653. Hence the result of division in the diamagnetic metals 

 is altogether of a nature to confirm the conclusion,, that the 

 effects produced by them are due to induced currents moving 

 through their masses, and not to any polarity correspondent 

 in its general nature (though opposed in its direction) to that 

 of iron. 



2664<. In the third place (2656.), another and very im- 

 portant distinction in the actions of a diamagnetic metal may 

 be experimentally established according as they may be due 

 either to a true polarity, or merely to the presence of tempo- 

 rary induced currents ; and as for the consideration of this 

 point diamagnetic and magnetic polarity are the same, the 

 point may best be considered, at present, in relation to iron. 



2665. If a core of any kind be advanced towards the domi- 

 nant magnet and withdrawn from it by a motion of uniform 

 velocity, then a complete journey or to and from action might 

 be divided into four parts; the to, the stop after it; the from, 

 and the stop succeeding that. If a core of iron make this 

 journey, its end towards the dominant magnet becomes a pole, 

 rising in force until at the nearest distance, and falling in force 



* Taylor's Scientific Memoirs, vol. v. p. 129. I do not see a date to the 

 paper. 



