192 



obtained, and that it differed materially, 

 in some eases, from the linear equation 

 generally used, but was of a character 

 not convenient for practical use. 



Mr. Elihu Thomson, in regard to the 

 relation between the width of the field- 

 poles and the armature-winding, observed 

 that the author's statement that " width 

 of poles equal to half the pitch, smooth 

 armature, and winding covering only one- 

 half the surface," was most frequently 

 met with in practice, was without doubt 

 true. But was it the best practice? 

 While designing such machinery, it oc- 

 curred to him that a higher yield in 

 electromotive force would be had from a 

 given armature, particularly under full 

 load, or "dynamic" working, as dis 

 tinguished from open circuit, or u static " 

 condition, if the open space in the 

 interior of each coil was made less than 

 the width of the pole-face. It was seen 

 that this must result as a consequence of 

 the crowding or distortion of the field- 

 lines forward by the currents in the 

 armature-coils, having the practical effect 



