Brown — Note on the Change of Length in Nickel Wire. 301 



contraction for the corresponding direct magnetic field, that is, the A, C. 

 contraction is about 1'61 times the D. 0. contraction with the smallest load 

 on, 1-58 times for the middle load, and 1-49 times for the greatest load. 

 Again, if we were to plot the A.O. contraction as ordinates, and the corre- 

 sponding values of the maximum alternating fields as abseissse, the multiplying 

 factors would be 1'56, 1"50, and 1-37 respectively, in the order of the loads 

 from the low to the high. 



For assistance in reading tlie microscope I am indebted to the Eev. Br. 

 P. V. liyan, a third-year student in Physics of tliis College. 



SOIPNT. PROC. R.D.S., VOL. XIV, NO. XXI. 8 B 



