Abstract: A mechanical timepiece has a power source comprised of a mainspring for undergoing rewinding movement to generate a rotational force. A front train wheel undergoes rotation in accordance with a rotational force generated during rewinding movement of the mainspring. An escapement/speed-control device controls rotation of the front train wheel. The escapement/speed-control device has a balance with a hairspring for undergoing alternately repeating rotational movement in left and right directions. An escape wheel and pinion undergoes rotation in accordance with rotation of the front train wheel. A pallet fork controls rotation of the escape wheel and pinion in accordance with rotational movement of the balance. A switch mechanism outputs an ON signal when a rotation angle of the balance reaches a predetermined threshold angle or greater, outputs an OFF signal when the rotation angle of the balance does not exceed the predetermined threshold angle.

Abstract: In a radio communication system in which local office selection signals respectively asigned to a plurality of local offices are sent in a time sharing basis from a central office to the local offices together with a voice signal, each local office is provided with local office selection signal judging means and a transmitter for transmitting a response signal to the central office when the received selection signal is assigned to the local office. The central office is provided with a response signal judging means for judging that a response signal received thereby was sent from which one of the local offices and display lamps arranged side by side for displaying the local offices that have responded.