DIAGRAM FOR COUPLED SYNCHRONOUS MOTORS 171 



mmerous series of points, these may be considered as being " levels " 

 a topographical plan, and lines connecting together the points 

 it the same " levels " can be drawn like the " contour " lines on 

 jpographical plans. Between any two such lines of constant 

 Dwer, other lines of constant power of intermediate value can be 

 iwn by interpolation in the well-known way. 



