Soft Iron, especially with weaker decomposing -powers. 

 1 



43 



if <t= — , *. The application of these formula? to the two 



\/r 2 -d 2 ™ 



ellipsoids above mentioned gives the following Tables : — 



Table I. 



R. 



Jc. 



R. 



Jc. 



R. 



Jc. 



2-40 



30-5 



331 



1190 



53-3 



110-9 



5-20 



40-8 



339 



1187 



59-2 



113-0 



120 



72-5 



38-6 



120-2 



98-4 



89-3 



211 



99-1 



45-6 



120-4 



176-2 



62-9 



241 



113-4 



51-9 



119-1 



3007 



39-7 



Table II, 



R. 



Jc. 



R. 

 116-5 



Jc. 

 76-8 



R. 



Jc. 



5-18 



201 



1722 



711 



8-71 



22-6 



148 



64-9 



2034 



606 



10-30 



231 



213 



471 



2044 



6-05 



14-30 



28-4 



240 



41-9 



2449 



5-37 



22-2 



45-3 



250 



40-7 



2981 



4-28 



26-9 



54-3 



379 



27-9 



3013 



4-23 



34-4 



83-4 



455 



23-8 



3464 



3-73 



38-5 



94-5 



495 



21-9 



3864 



3-36 



47-0 



98-1 



610 



18-1 



3971 



3-25 



49-2 



107-5 



749 



14-9 



4229 



3 05 



64-9 



107-3 



935 



12-3 



4541 



2-86 



97-2 



87-0 



1339 



8-88 







Hence becomes evident the remarkable fact which, it seems 

 to me, has not yet been duly recognized, that with the lower 

 values of R the magnetizing-function has an ascending course, 

 and with a certain value of R reaches a maximum. We 

 see further from these Tables that with a very long and thin 

 rod, if it is magnetized by a force not too great, the magnetic 

 moment increases not as is usually assumed, nearly proportion- 

 ally, but much more rapidly, and between certain limits of the 

 force is nearly proportional to the cube of it. 



This is to be seen even from some of Joule's experiments f, 

 whose attention, however, was chiefly directed to the permanent 

 magnetism of the rod. Further, Wiedemann J remarked that, 

 with rods of moderate thickness, the magnetic moment increases 

 a little more quickly than the magnetizing-force. From the series 

 of experiments No. 1 of Von Quintus Icilius the fact comes out 

 very strikingly and at once ; prominence was given to it by the 

 observer himself : he seems, however, to be surprised that the 



Neumann, Crelle's Journal, vol. xxxvii. p. 44. 



t Phil. Trans. 1856, p. 287. 



Galvanismus, vol. ii. p. 297- 



