294,546. British Thomson-Houston Co., Ltd., (Assignees of Kell, R. D.). July 25, 1927, [Convention date]. Synchronous movements and synchronism-indicators.-A copying-telegraph receiver has means 18 for receiving and separating a plurality of impulse trains, means 25 for driving the apparatus, manually operated means 32 for controlling the speed of the driving-motor by varying the intensity of the exciting current, and means for indicating when the motor is in synchronism with the variations in magnitude of one of the sets of impulses. The transmitter (Fig. 1, not shown) transmits sets of electric impulses which are respectively dependent on the speed of the transmitter through a contact driven together with the transmitting-drum and on the variation in the light-value of the successive elemental portions of the picture to be transmitted. The speed of the driving motor at the receiver is controlled by a tapping-key 32 and synchronism is indicated visually by a disc 30 rotated by the motor and provided with an opening 31 for viewing a light 20 which is controlled by the received impulses in dependence on the speed of the transmitter and by a switching-device 21 driven with the receiving-drum 23.