362 Recent Discoveries in Magnetism and Electricity. 



below and at a right angle to the platinum wire, it will be re- 

 pelled or driven downwards ; if we now remove the needle 

 keeping it in the same position, so that its north pole may be 

 above the platinum wire, it will then be attracted towards it. 

 If the electric poles be reversed, these phaenomena will also be 

 reversed. 



If we suppose the conjunctive platinum wire to be vertical, 

 instead of horizontal, and in that position approach it with 

 either end of the magnetic needle, the needle will oscillate, but 

 will not be permanently attracted or repelled by any part of 

 the conjunctive wire. — Professor Oersted. 



2. If a small steel bar be attached to the conjunctive wire, and 

 parallel to it, it does not become a polar magnet ; but if it be 

 attached transversely, it does become polar, and it becomes 

 north and south, or south and north, according to the direction 

 of the supposed electric current traversing the conjunctive wire, 

 according as one or the other end of it is positive or negative. 

 Thus supposing W to represent the platinum conjunctive wire 

 of the Voltaic apparatus, and N S a wire of iron attached 



W^ 



transversely to it, the latter becomes permanently magnetic. — 

 Sir H. Davy. 



3. If we suppose a second conjunctive wire parallel to, and si- 

 milarly situated with, the first, as in this figure, those wires will 



PI z:::::^!:^ 



P I I N 



attract each other ; but if one conjunctive wire be traversed by 



