224 PECULIARITIES IN THE MAGNETISM 
40. We next inquire into the changes that take 
place in that pole of the magnet which the iron 
approaches; or rather, with which it is in con- 
tact: and we find that it advances upon the ex- 
tremity of the bar. Hence we arrive at another 
general law, viz. When a mass of iron is brought 
into contact with a bar magnet, exterior to either 
pole, in the line of the axis, it occasions a trans- 
placement of both poles towards itself. 
41. If, instead of placing the iron in contact 
with that pole of the magnet which is most re- 
mote from the needle, we were to place it by the 
side of the nearest pole ; the needle would indi- 
cate a lateral movement of the latter pole towards 
the iron. 
42. With the assistance of these facts developed 
by the attachment of soft iron to the poles of a 
magnet, in connexion with the well known fact 
that the resistance to magnetic excitement in 
steel is much greater at a hard than at a soft 
temper, we find a simple and satisfactory explana- 
tion of the apparent mystery which the lateral 
motions of the magnetic poles, towards the point 
of heat, at first involved, (30, 31.) 
