82 ELEMENTS OF ELECTRICITY AND MAGNETISM. 



the lines of force in the field is greatly altered ; in fact, the field 

 becomes the resultant of two fields, namely, the original field and 





Fig. 47. 



the field due to the piece of iron which has become a magnet. 

 Thus, Fig. 47 shows the effect of a small piece of iron upon the 





Fig. 48. 



magnetic field between two flat-ended magnet poles. In the ab- 

 sence of the iron the field is as shown in Fig. 48. The effect of 



