Page:Popular Science Monthly Volume 22.djvu/347

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TIME-KEEPING IN LONDON.

broken, the relay-bars go back to their normal position, the train-work moves away the cam (C), and restores the vertical bars to connection with their instruments.

The apparatus which effects the shunting at one o'clock is somewhat different in construction. The pin (P, Fig. 9) falls into the notch (N'),

PSM V22 D347 Diagram of electric connections between clock and chronopher.jpg
Fig. 9.—Diagram showing Electric Connections of Clock with Chronopher.

a pin (p) on the wheel (W) coming against the arm (I) of the forked lever (Y) raises the flexible arm (G) against the upper contact (D), so that the circuit of the local battery (U) is closed through the starting magnet (M), which operates the one o'clock train-work.

Wires which receive both the ten and one o'clock signals pass through both switching arrangements.

For the hourly currents on metropolitan lines the relay (V''') serves, by closing the circuit of the battery (U) at the contact (K), the rest of the apparatus remaining inoperative.