21 Electric Motor Control Apparatus, Including Speed Controls for Series, Shunt and Compound Electric Motors, Embodying Adjustable Transformers, Rectifiers, Chokes, Switches, Braking and Other Resistors, and Lamps; Adjustable Autotransformers, Including Output Terminals for Connection to Electric Heaters, Ovens, Electric Lights and Lamps, Motors, Power Supplies, Rectifiers, Voltage-Aging Equipment for Lamps, Vacuum Tubes and Dry-Disk Rectifiers; Motor-Driven Autotransformers Including Motors of the Servo Type, Coupling Gears, Phase Shift and Other Capacitors, and Limit Switches; Voltage Regulators Including Automatic Voltage Regulators Embodying Adjustable Autotransformers and Servomechanism for Controlling the Setting Thereof; Multiple-Phase Voltage Regulators, Including Single and Three-Phase Regulators; and Cabinets, Cases, Chassis, Electric Power Cords and Electric Lines, Dials, Control Knobs, Terminal Strips, Brushes and Connectors for the Above-Named Transformers, Regulators and Control Apparatus