1012] on ITijih Froqwnnj Currents. 405 



able to show you some photograplis of a 100,000 frequency machine 

 and <rive you some details as' to its construction. The alternator is 



Fig. 4. — Section of Alexanderson's 100,000 -^ Alternator. 



of the inductor type. The rotating part consists of a steel disc having 

 300 slots cut round its edge so as to leave 300 steel teeth. Each 

 of these steel teeth acts in turn to close the magnetic circuit between 



