Mapping the Magnetic Field. 



377 



In the preparation of this plate, a marked distinction was 

 noticed between the north and south poles of the magnets. 

 This difference is fairly well shown in the cut. 



Fig. 4. Unlike Poles. 



The alternate poles beginning with the pole upon the left 

 of fig. 7 are south poles. The filings in the neighborhood of 

 these poles are in every case more erect and exhibit greater 

 intensity of action than those at the north poles. Whether 

 this is due to a real difference between the north and south 



Fig. 5. Like Poles. 



poles of the magnet or is to be explained as a mere coincidence, 

 can only be determined by more careful observations than 

 those which I have yet made. 



