﻿Waves of Magnetic Flux along Iron Wires. 457 



of the specimen, other things being equal, increases the space 

 rate of retardation of the flux near the origin. 



There might seem to be a discrepancy when the values of" 

 /; for # = in Tables XIV., XV., XVI. relative to the first 

 harmonics of their magnetizing currents are compared with 

 the value of F in Table XVII. relative to the continuous 

 current producing F . The iron seems to be quite as per- 

 meable under alternating magnetization as under continuous. 

 This apparent discrepancy will disappear (and this remark 

 will apply to the other specimens) when it is remembered 



(a) that the form of the current wave is peaked and its max. 

 ordinate is greater than the amplitude of its first harmonic, 



(b) that the form of the flux-wave is flat and its max. ordinate 

 is less than the amplitude of its first harmonic. 



Thus the max. values of C and F for the different values 

 of T in the above are as follows : — 





00 



•0545 



Cmax. 



Fmax. 



•1844 

 2220 



•1854 



21 GO 



034 ( -0234 

 •18.30 -1866 

 21 GO 2034 



12. Eddy currents must play an important part in the 

 phenomena under consideration, and their effects in this con- 

 nexion may, in a general way, be explained as follows. If 

 the vector OF (fig. 10) represent the resultant flux down 



Fisr. 10. 



any cylindrical portion of a rod, the E.M.F. produced by its 

 variation in a circuit in the rod round the outside of this 

 cylinder, being in quadrature with OF and behind it in 

 phase, may be represented by a vector FE where the angle 

 OFE is a right angle. This E.M.F. generates an eddy 



