CONTROL FORK:
Of course, the sending machine and the receiving machines must run in exact synchronism. This synchronous control of the sending and receiving motors is maintained by the vibration of a rather heavy fork at each station, and adjusted to beat together, with such slight automatic correction by radio as may be required to keep all receiving forks in step with the fork of the station which at the moment is sending. It is a very simple and dependable mechanism, by which any number of motors, of any size, separated by any distance, can be made to run in synchronism.