Brown — The Change of Length in Nickel Wires. 



45 



Table V. 



Rigidity = 708 x 10 6 grammes per sq. cm. 

 Load = 2 x 10 s grammes per sq. cm. 



From Tables IV and V, by considering the values of the contraction 

 obtained with the wire in this soft state, when in the magnetic field of 200 

 units, we find, for a longitudinal magnetic field, that when the load is increased 

 16 times the contraction is decreased about 15 per cent., that is half as much 

 again as when the wire was harder. 



For the same magnetic field of 200 units, when the frequency of the 

 applied alternating magnetic field is increased 6 times, the contraction is 

 increased about 27 per cent, for the middle load and 19 per cent, for the high 

 load, which is about double that obtained with the hard wire, that is for a 

 difference in the rigidity of about 12£ per cent. 



Three other wires having rigidities intermediate to the two already 

 mentioned were tested in a similar manner, when they were under two 

 different longitudinal loads, and when they were subjected to the influence 

 of longitudinal magnetic fields, and alternating magnetic fields of frequency 

 150 per second only. The results so obtained are given in Tables VI, 

 VII, and VIII, the numbers in the tables being as before the values of 



— x 10"' cms. 



