248 



METHODS OF CALCULATION 



the shaft of the field magnet. It presents a supplementary air-gap of 

 considerable reluctance around the shaft, and this air-gap is traversed 

 only by the direct reaction. The coefficient of direct reaction is 

 therefore rendered smaller than that of the transverse reaction, and 

 if the supplementary stray fields J/i, analyzed above, are not exag- 

 gerated, C will remain below T. 



Those theoretical diagrams are not, therefore, liable to criticism 

 which show C below T. To propose placing C always on T, as 



FIG. 7. 



Professor Arnold has done, 1 is contrary to the purpose of this method, 

 namely, the calculation of the effects of saturation and of distortion 

 according to rational principles. 



The Case of a Saturated Armature. (Fig. 7.) The theory 

 of two reactions permits also of treating the case of a saturated arma- 

 ture, by employing with the total characteristic, the characteristic of 

 the armature alone (comprising the armature, air-gap, and pole pieces), 



1 E. Arnold, Elek. Zeit., 1902, page 250. 



