258 DESCRIPTION OF A MAGNETIMETEB, &C. 



13. Iron is rendered magnetical, if a stream of the electric 

 fluid be passed through it, when it is in a position nearly cor- 

 responding with that of the magnetic axis ; but no effect is 

 produced, when the iron is in the plane of the magnetic equa- 

 tor. 



Exp. 1. — Bar, No. 1., freed from magnetism, and placed upright in 

 the prime conductor, had a silent stream of electricity di-awn from 

 it by Dr Traill, first with a pointed wire, and then with the 

 point of a cone of wood. In both cases the upper end became a 

 south pole, and the lower end repelled the needle 6°. Sparks drawn 

 from the bar by a piece of metal answered the same purpose. 



Exp. 2. — The prime conductor being tiuned into an east and west 

 position, the bar was introduced into an orifice in the end of it, and 

 consequently obtained the position of the magnetic equator. A 

 stream of electricity di-awn from it with a cone of wood, or with a 

 piece of metal, did not render it at all magnetic 



Some experiments of a similar nature to those which are gi- 

 ven in illustration of the last three propositions, were attempt- 

 ed with a galvanic apparatus, for the purpose of ascertaining 

 whether some of the electro-magnetic phenomena, lately ob- 

 served by Mr Oersted, be not referable to the position of the 

 iron or steel made use of in his experiments ; but the power 

 of the apparatus I employed, though sufficient to produce stri- 

 king effects on the position of a compass needle, was not ca- 

 pable of magnetising iron ; consequently the experiments 

 made with it did not prove satisfactory. 



XVIII. 



