105 



stion, and Fig. 25 an elevation, is a 

 edification of the well-known turbo- 

 jctric generator of the Hon. Charles 

 irsons. It is the only example of a 

 •polar alternator with drum arma- 

 re, the arrangement being inter- 

 sdiate between that shown in Fig. 4 and 

 g. 5, that is to say the polar surfaces, 

 though not completely surrounding the 

 mature, yet embrace more than half 

 e circumference. The armature core 

 nsists of thin iron plates insulated 

 ith paper and mica, and threaded upon 

 e spindle. The wire is laid on in a 

 ogle-coil, the ends being brought to 

 70 collecting rings in the usual way. 

 i a 75-kilowatt alternator, giving 75 

 nperes at 1,000 volts terminal pressure, 

 Le armature core is 7 inches in diameter 

 j 30 inches long, and the core of the 

 3ld-magnets, which are of cast-iron, is 5 

 ches by 28 inches. The armature coil 

 mtains one hundred and ten active 

 ires, 127 millimeters in diameter, giving 

 current-density of 6,000 amperes per 

 juare inch. The armature resistance is 



