Page:Popular Science Monthly Volume 22.djvu/351

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error the hand of the time-piece must be set back five minutes. When the setting is done, no further attention is required, all else being automatic.

The distributor (shown in Fig. 11) consists of twelve contact-springs, each connected with a line of wire running through a district of London, and twelve contact-screws, each connected with a battery.

PSM V22 D351 Time setting of london clocks from a central box.jpg
Fig. 11.—Test-Box.

The springs converging to the center press up against a small plate, one inch in diameter, which is controlled by an electro-magnet in the circuit of the current which the standard clock sends out hourly. When the signal comes, the plate is pulled down and presses every