Ferromagnetic Wires by Magnetization. 315 



square millimetre the elongation is already diminished by 

 one half of its value corresponding to no tension. 



To study the effect of heavy loading a wire of O50 mm. 

 thick was made of the same alloy. After a moderate an- 

 nealing it was subjected to an experiment to see whether it 

 becomes shorter than the initial length when magnetized 

 under a heavy loading: This actually occurred as oiven in 



fig. 11. 



TVith a tension of 2 6' 9 kilograms per square milh- 



Fiff. 11. 



T = I s e 6 c 



300 



263 



sc: 



00 



6 :: 



7W 



metre the length of the wire decidedly shortens when mag- 

 netized. Since the degree of annealing is different in the 

 thick from the thin wire, the changes of length in these two 

 wires for the same field and tension do not exactly coincide 

 with each other. 



The curve showing the relation between the change of 

 length and the tension under constant field is shown in 

 fig. 12 ; here we notice that the rate of the diminution of the 

 change of length becomes less as the tension is increased. 



Fig. 12. 



•:: 



J 











& k>vU. ; i 





-v,X ^ \^<> 







T| 



With another specimen of nickel-steel (35 per cent. Ni) 

 the nature of the change of length and the effect of tension 

 on it are generally the same as those of the former metal, as 



Phil. Mag. S. 6. Vol. 4. No. 21. Sept. 1902. 2 A 



