222 



HENRY A. KOWLAND 



the armature. Of course this form belongs both to the Gramme ring 

 and the Siemens armature. Most modern machines are of this nature, 

 either Gramme or Siemens, and we may consider them both one if 

 we wish. 



We will now proceed with respect to the field in this form of magnet 

 (Fig. 3). The lines of force proceed down the magnet, and are sup- 

 posed to go across here (a &), where wires wound around the revolving 

 armature cut them, and so produce a current. It is evident that any 

 lines which escape across this open space (arrows) are lost. If there 



FIG. a. 



FIG. 4. 



was any leakage of the wire around the magnet, the current, instead of 

 going around the magnet, would go off somewhere else, and we should 

 consider the machine defective because there was a loss of the current. 

 Sq if any of these lines of force, instead of going directly across there 

 (a &), go across the open space (arrows), as they naturally would do, all 

 those lines of force are lost, and we would have to add so much more 

 current in order to make up for this outside loss. I have an illustra- 

 tion of such losses of lines of force from a drawing, which I will give 

 you (Fig. 4). 



This machine has two magnets one above and one below. The lines 



