OR, PLAIN TEACHING. 139 



any other cause, a green flag is 

 held up, 12. If it be desired 

 that the engine should slacken 

 speed, and proceed with caution 

 from any defect, or from a curve 

 in the rails, the green flag is 

 lowered, 13. But if it be desired 

 that the engine should stop, a 



13 14 



447. c 448. 



red flag is shown. Another sig- 

 nal, meaning " all right," con- 

 sists of holding the right arm 

 in a horizontal position, pointing 

 across the line, 14. The caution 

 signal to slacken speed, consists 

 of the policeman facing the ap- 

 proaching train, one arm being 

 held upright to its full extent, 15, 



15 16 



The danger signal, " stop " is 

 shown by the policeman facing 

 the approaching train, and hold 

 ing both arms up, 16. 



Signal posts are erected on the 

 up and down lines, at interme- 

 diate stations ; red boards and 

 green boards are used as day 

 signals, and red and green lights 

 are employed, instead of the 

 boards, by night. On a train or 

 engine passing an intermediate 

 station, the green signal is ex- 

 hibited for ten minutes, to denote 

 that a train has passed within 

 that period. On a train stopping 

 at a station, the red signal is 

 shown for five minutes after its 

 departure. 



Engine signals consist of white 

 and coloured boards by day, and 

 white and coloured lights by 

 night, placed before and behind 

 the train, to denote its character, 

 n Tall posts, 



with moveable 

 boards affixed 

 to them, 17, 

 are employed 

 at those points 

 where it is 

 necessary to 

 observe the 

 signals at long 

 distances. A 

 board being 

 depressed 

 means caution ; 

 being up, 

 means all clear. 

 If the board 

 points across 

 451. the up line, it 



refers to that line, or the contrary. 

 Boards of various shapes and 

 colours are employed, 18, 19. 

 They are painted of different 

 colours on the opposite sides, and 

 indicate danger or safety accord- 

 ing to the colour presented tu 



