Smithsonian Report, 1924. — Whitney 



Plate 2 



. A Demonstration ofthe Radiotron Prin- 

 ciple. Electron Current from the Hot 

 Filament to the Plate of the Radiotron 

 Tube on the Left Is Made to Light the 

 Incandescent Lamp at the Right. This 

 Current Can Be Stopped by Inducing a 

 Negative Charge on the Vertical An- 

 tenna Wire Which Is Connected to the 

 Grid 



2. A Demon<5tration of the Sensitiveness of a Magne- 

 trg j i ube to a magnetic field. when this two- 

 Element Tube Is Suitably Arranged, Its Position 

 WITH Respect to Terrestrial Magnetism Influences 

 THE Meter Reading 



