88 



This in turn is supported by, but insu- 

 lated from, the central armature- ring. 

 There are two bobbins to each carrier, 

 which forms the metallic connection be- 

 tween their inner ends. There is thus a 

 double insulation for the coil, first that 

 of the conductor against the core and 

 bobbin-carrier ; and secondly, that of the 

 latter against the body of the machine. 

 The winding of the coils is such, that the 

 current passes through the armature in 

 two parallel circuits, by which arrange- 

 ment the terminals of the armature are 

 brought to opposite points of a diameter; 

 and the connection between adjacent 

 coils is made automatically, by the act of 

 inserting and bolting up the coil so that 

 it is impossible for a workman, when 

 replacing a coil, to make a wrong con- 

 nection. The mean width of poles is 

 approximately equal to half the pitch, and 

 the width of coils is also equal to half the 

 pitch, so that, according to the table on 

 p. 22, the coefficient is 2.300. The follow- 

 ing are the principal data for a 150-HP. 

 machine: 500 revolutions, 46.5 amperes, 



