386 Mr. F. J. Smith on the Effects of Magnetism 



end of the axle of the mirror. This led to the result described 

 in (25). 



6. On reversing the current the direction of torsion was 

 not reversed. A similar rod, with the same amount of torsion 

 in the opposite direction, was further twisted by the magnetic 

 fcrce in the direction of the initial torsion. When the current 

 was off, the rod returned to its original position. Subsequent 

 experiments showed that there was a limit to this torsion by- 

 magnetism. 



7. The next experiment was arranged to find out any re- 

 lationship which might exist between the magnetizing force 

 and the amount of torsion. 



An iron rod 0*16 centim. diameter and 50 centim. long, 

 with torsion as before (5), was successively magnetized with 

 an increasing force, shown in the column headed H, the 

 corresponding deflexions are shown in the next column. 



H. 



Deflexions. 



H. 



Deflexion. 



1902 



3-0 



114-12 



10-1 



28-53 



40 



123-63 



10-1 



38-04 



5-2 



133-14 



10-1 



47-55 



6-1 



142-65 



101 



57-06 



7-1 



152-16 



10-1 



66-57 



8-0 



161-67 



10-1 



76-08 



8-8 



171-18 



10-1 



85-59 



91 



180-69 



90 



95-10 



100 



190-20 



9-0 



104-61 



100 







The table indicates that for low values of H the deflexion 

 is nearly proportional to the force H, and that after a certain 

 value it becomes permanent and then begins to fall off, 

 indicating an untwisting. I am now arranging a large 

 battery of accumulators for the production of very much more 

 intense magnetic fields, so that I may find out, the rate at which 

 the wire untwists after the maximum of deflexion is reached. 



The last experiment was repeated with a similar iron rod, 

 subjected to one complete twist in its length instead of seven, 

 and the followino; results were obtained : — 



H. 



Deflexions. 



H. 



Deflexions. 



28-53 



1-0 



11412 



3 - 5 



38-04 



20 



123-63 



34 



47-55 



30 



13314 



31 



57-06 



3-1 



142-65 



30 



66-57 



35 



152-16 



30 



76-08 



3-5 



161-67 



3-0 



89-59 



3-75 



171-18 



3-0 



95-10 



4-00 



180-69 



30 



104-61 



375 







