Abstract
II.
WE have now to speak of the use made of the time signals beyond the Observatory walls, and will first refer to the hourly currents passing to the Post Office. The original time-distributing apparatus was comparatively simple; afterwards Mr. C. F. Varley devised the chronopher, an elaborate system of switches and relays provided with an accurate clock for opening and closing the switches at the proper times, and forming together a complete automatic system; but on the transfer of the central telegraph station from Telegraph Street to the new building in St. Martin's-le-Grand, it was found necessary to add a second and much larger chronopher, shown in the accompanying drawing. It is to this apparatus that the Greenwich wire is led, and by which the single Greenwich current is simultaneously retransmitted on many different lines. These lines may be considered as divided into four groups:—1, the metropolitan; 2, the short provincial ; 3, the medium provincial; and 4, the long provincial. The first group consists of wires passing to points in London; the second of wires passing to towns within a moderate distance of London, as Brighton, &c.; the third of wires passing to greater distances, as Hull, &c.; and the fourth of wires passing to towns or places at a considerable distance, as Belfast,1 Edinburgh, Guernsey, &c. In each of the four groups the London ends of the several lines are brought into direct connection, each group having its separate battery and relay. On these four relays (the two at the left hand and two in the centre of the six shown) the current from Greenwich acts, and in each relay circuit the local battery current so divides that a portion of it passes out on every wire of the group.
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The Greenwich Time Signal System . Nature 14, 110–113 (1876). https://doi.org/10.1038/014110a0
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DOI: https://doi.org/10.1038/014110a0