Your Neiv Servants: The Electronic "Watchmen" 1 19 



screen, or grid, of wires. This can be thought of as a Venetian 

 blind. Positively charged, the same as the filament, the blind 

 is open and electrons pass through freely. But if it is gradu- 

 ally made negative, this is equivalent to closing the blind; and 

 the stream of electrons is reduced and finally stopped. Such 

 tubes made possible a new function that of amplification. 

 .A very small current on the grid can control the flow of a 

 larger current through the tube and, because of the instantane- 

 ous response, the quickest variations in the grid circuit are 

 immediately reflected in the flow from the plate. . . . 



"Another electron tube has found application in such varied 

 tasks as controlling the lighting for a dance number on the 

 stage of the Radio City Music Hall and welding the metal 

 shell of a bombing plane. This is the thyratron. In one of its 

 largest sizes, it will control 300,000 watts of power with less 

 than half a watt applied to its grid!" 



After the war the average man will reap the benefits not 

 only of better electronic equipment of his own but of the 

 effect of the speed-up on the production of many other arti- 

 cles by the introduction of electronic devices in factory pro- 

 duction. Just as the machine age in manufacturing made the 

 luxuries of yesterday the conveniences of today, so the elec- 

 tronic age in manufacturing will make the luxuries of today 

 the conveniences of tomorrow. 



Radar 



When droves of German Stukas came over England in the 

 historic Battle of Britain, Radar teamed up with R.A.F. Spit- 

 fires and Hurricanes to save the day. Radar warned the Eng- 

 lish pilots long before the German planes were overhead. It 

 enabled "the few" to conserve , their strength, to get off the 

 ground in time, to concentrate their forces where needed, and 

 to fly at an altitude which would give them the needed advan- 

 tages over enemy forces which vastly outnumbered them. 



