Abstract :
AUTOMOBILES, SHIPS, AIRPLANES, certain radars, and gun fire control systems are examples of complex devices built for human operation. As these machines are developed and improved they tend to become more automatic, with the man doing less to make them work. However, men will continue to play an important role in such activities for some years to come. So long as they do serve as controlling links in the electromechanical devices which they construct for their business, pleasure, or destruction, it will be necessary to understand how they operate as a part of these devices.
