One of the earliest technology start-ups, Raytheon was established in Cambridge, Mass., home of the Massachusetts Institute of Technology, as the American Appliance Company. The company\'s founders were Vannevar Bush, who would become dean of MIT\'s School of Engineering; Laurence Marshall, an engineer; and Charles G. Smith, a scientist who had done work on the electrical properties of gases. Their revolutionary innovation was the S gas rectifier tube, a device that eliminated one of the cumbersome expensive batteries that previously powered home radios. The tube transformed the radio into an affordable \"must-have\" appliance that could be plugged into a wall socket, turning radio into a true mass medium that brought the world into America\'s living rooms. Raytheon quickly moved to the forefront of innovation in the electronics industry. During World War II, Raytheon employees contributed to the war effort. They supplied 80 percent of the magnetron tubes used in U.S. and British radars and developed parts for the crucial proximity fuse in antiaircraft shells, among other equipment. After the war Raytheon began offering civilian products, the microwave being among the most famous. Raytheon engineer Percy Spencer discovered microwave cooking when, as he stood in front of an active magnetron, a candy bar in his pocket began to melt. Intrigued, he sent out for popcorn kernels – and they began to pop. With that, a new appliance was soon on its way.