Discoveries and inventions of the nineteenth century (1905)
Routledge, Robert · London : G. Routledge and Sons · leaf 137
proceed cautiously; when the arm is down theline is clear. These signals, of course, are not capable of being seen at night,when their place is supplied with lamps, provided with coloured glasses—red and green—and also with an uncoloured glass. The lamp may havethe different glasses on three… … Fig. 48.—Signal-box on the North London Railway like spectacles in front of it. The meanings of the various coloured lightsand the corresponding semaphore signals are these : I 1 WhiteGreenRed . All rightCaution .Dansrer . Go on. Proceed slowly.Stop. A very clear account of the mode of working…
Inventions
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