Patent GB-191124723-A (GB)
Title: Improvements in and relating to the Synchronisation of Clocks.
Inventor: PARSONS ISAAC HARDY
IPC: G04C11/00
Filed: 1911-11-07
Granted: 1912-11-07
Abstract: 24,723. Parsons, I. H., and Ball, A. E. J. Nov. 7. Electric clocks.-Relates to a method of synchronization, in which a clock having a slight gaining rate is automatically stopped at a certain time by the completion of a circuit through a switch, the circuit also including another switch which is opened at the synchronizing instant to restart the clock. According to this invention, the svnchronized clock is a transmitter which controls a series of secondary clocks, one of these_ actuating t h e switch that completes the circuit. In the arrangement shown diagrammatically in Fig. 4, a standard clock H, or a secondary clock I operated by it. closes a switch J, J<1> at a predetermined time; shortly afterwards, a secondary clock N, controlled by the transmitter M which is to be synchronized, closes a switch N<1>, N<2>, and a circuit through an electro-magnet A being thus completed, the wheel-work of the clock M is stopped. Precisely at the instant of synchronization, the switch J, J<1> is opened, and the clock M is started again. To stop the clock M. the armature of the magnet A may hold the driving-pawl carried by the pendulum out of engagement with the ratchet-wheel F, or may hold the back stop click G out of engagement with the ratchetwheel, or the armature may be provided with a catch adapted to engage with the teeth of one of the wheels of the train. The control may take place every hour or at longer intervals, contacts operated by 12-hour or 24-hour wheels being introduced in series in the circuit where necessary. A synchronized transmitter may be so controlled that it is kept a few seconds slow, and thus serves as a stand-by or second transmitter for a turret-clock such as is described in Specification 20,878/07. For this purpose, there are provided additional contacts operated by the transmitter itself, which complete the circuit at any desired instant after the contacts N<1>, N<2> are closed. Several sub-transmitters such as M may be under the control of one prime-transmitter H, which may itself be controlled from a standard source. Fig. 5 illustrates a method applicable to the control of a prime-transmitter from Greenwich or other standard source. A secondary clock I, operated by the transmitter H, has a cam S which lifts a spring-controlled bell-crank lever S', allowing a switch R, R<1> to close; when a second switch T, T' operated by the secondary clock is also closed, a circuit is completed through the electro-magnet A, and the clock H is stopped. The lever S<1> is held in the raised position by the armature of an electro-magnet S<5>, until, at the synchronizing moment, a current sent out from the standard source energizes the magnet, or a current already flowing is suddenly reversed, whereupon the lever S<1> is released, the switch R, R' is opened, and the clock H is re-started. If the current from the standard source fails to flow throlgh the magnet S<5>, the circuit through the magnet A is automatically broken by a time-lag switch G'. This comprises an electro-magnet U, having an armature V, one end of which is a toothed sector gearing with a train of wheels W controlled by an escapement, the other end normally holding contacts Y, Y<1> together. The armature allows these contacts to separate if its attraction by the magnet U is unduly prolonged, a total stoppage of the clock H being thus prevented. Specifications 24,620/04 and 919/07 are referred to.