Z'ZS H. R. Ha/mley and A. L. Rossiter : 



Where X is the space average of eddy-current loss. 



X the thickness, 



p the specific resistance, 



fx. the permeability being assumed constant. 



From this the eddy-current loss per c.c. per cycle may be 

 reduced to the form^. 



E = — V-' 

 6pT^ 



where V. = Bj[l + 9l>.f + 25^,- -l- ]i 



The statical hysteresis (U) was determined by Ewing and 

 Klaasen's ballistic method, and from the results the 8teinraetz co- 

 efficient o" obtained was plotted against the maximum induction by 

 the use of the formula — 



U = crBiL. 



In order to determine the value of U for alternating cur- 

 rents, it was assumed that it was equal to that obtained by the 

 statical method for maximum induction equal to the maximum 

 value (B(,) of B. From the above mentioned graph and formula 

 U has been calculated for all inductions. 



Having obtained all these quantities, the values of I-U-E, 

 called by Fleming the ' kinetic hysteresis,' were calculated. 

 These as well as I, U, E, have been given for each experiment. 



The rings were prepared from the same sheet and were 

 made as nearly alike as possible. A thin sheet of waxed paper 

 separated each pair of discs and the wire used in the winding 

 was taken from the same coil. xVfter the laminae were well 

 cleaned the mean thickness was determined by the specific 

 gravity method. 



The specific resistance was determined by the " drop of 

 potential " method against a standard .1 ohm by means of a 

 Wolff's potentiometer. Experiments were n)ade on two samples, 

 one of length about 80 cms. cut from the sheet, and another 



