Your New Servants: The Electronic "Watchmen" 127 



Just as the phototube can distinguish shades of color with 

 a skill surpassing that of the human eye, so other electronic 

 watchmen can serve as inspectors of variations in weight and 

 thickness, and all other physical properties, and perform each 

 of these processes with superhuman skill and exactness. 



Electronic watchmen can scan a sheet of metal running past 

 at hundreds of feet a minute, detect a flaw no larger than a 

 pinprick, and mark the metal for discard at that point and 

 all without stopping the flowing of production. When a sheet 

 of metal is fed into a press, electronic watchmen can stand 

 guard over the press, stopping the machinery if the sheet 

 varies by a thickness far less than that of tissue paper. 



Amateur photographers know the saving in film that results 

 from the use of a light meter. This little meter, working on 

 the principle of a photoelectric tube, measures illumination 

 on a graduated scale and tells us how much light is reaching 

 the meter in terms of how much current flows from the 

 photocell. Thus we know how to set our cameras in order 

 to get good pictures in varying degrees of light. 



In the world of tomorrow this same principle will be used 

 to measure illumination in our homes, schools, and factories. 

 It will not be necessary for a human watchman to read the 

 meter and adjust our lighting for efficiency, for the electronic 

 watchman will take care of that, safeguarding our eyesight, 

 by turning on artificial illumination the moment daylight fails. 

 On winter days, when light is insufficient or fails quickly, 

 our fallible human judgment will not subject us to an hour 

 or more of eyestrain before we become aware that the light 

 has dimmed. 



The same phototube could be used to switch on the lights 

 when one entered a room and what price light bills? 

 switch off the lights when we left a room. There would be a 

 great future for the man who would perfect such a device 

 for installation in hotel rooms! The device could count the 



