RAILWAY CONSTRUCTION. 34* 



at cabin C, to obtain line clear, so as to allow the approaching 

 train to proceed on to C. If the previous train in the same 

 direction had already passed C, and there was not any obstruc- 

 tion on the line, the signalman at C would give line clear for 

 the DOWN train, and to do so he would turn his circular disc to 

 show the WHITE inscription ALL CLEAR, and then push in the 

 plunger of his C 1 instrument, lowering the DOWN or white arm, 

 K, of his own instrument to the position shown by the dotted 

 lines, which operation would at the same moment lower by 

 electricity the DOWN or red arm, G, of the instrument B 2 in 

 cabin B to the position of the dotted lines. The signalman at 

 B would then lower his starting signal, to allow the DOWN train 

 to proceed on towards C, and immediately the train had passed 

 the starting signal he would, by means of his bell or gong 

 advise the signalman at C that the train had entered the 

 section, or block BC, and the signalman at C would at once 

 turn his circular disc to show the RED inscription TRAIN ON LINE, 

 and use his plunger to raise to danger the DOWN or white arm, 

 K, of his own instrument, and at the same time raise by 

 electricity the DOWN or red arm, G, to danger in the instrument 

 B 2 in cabin B. The section BC would then remain blocked 

 until the DOWN train had arrived, or passed the station C, when 

 the signalman there would, by means of his bell or gong advise 

 the signalman at B that the DOWN train had passed out of the 

 section, and would turn his circular disc to show the GREEN 

 inscription TRAIN OFF, BUT SECTION BLOCKED. Both instruments 

 would then be in their normal positions, with the arms raised 

 to danger, and ready for further train operations. In a similar 

 manner for the UP-line trains on the section or block between 

 C and B, the signalman in B cabin would turn his circular disc, 

 and use his plunger to lower the UP or white arm, H, in his own 

 instrument, B 2 , and at the same moment lower by electricity the 

 UP or red arm, I, of the instrument C 1 in cabin C, the other 

 operation for train on line and train off being carried out for the 

 UP train in the same routine as for the DOWN train. The out- 

 door fixed signals, or distant home and starting semaphore 

 signals, have all to be worked to correspond to the block telegraph 

 signals, and as the latter are always received well in advance 

 of an approaching train, it follows that when the line is clear, 

 the outdoor signals can be lowered so as to allow a through or 

 non-stopping train to pass a block-telegraph station at full speed. 



