’DYNAMO-ELECTRIC GENERATORS. 
153 
owing to the fact that the armature coil is an electromagnet, 
and has poles of its own ; and consequently the position of the 
resultant poles influencing it (and therefore of the maxima and 
minima of potential) is a compromise between the two. In con- 
sequence of this, a slight inclination, technically called “ lead,'’ 
in the direction of rotation, has to be given to the brushes, and 
this “ lead ” increases with the speed of rotation, since by this 
the current in the coils of the armature is altered. 
