492
EXPOSITION AT VIENNA.
that there shall be no incongruity between the position of the signal and that of the switch.
In England the following regulation of the Board of Trade is in force, in respect to all newlines and new junctions upon old lines: —
“ The signal handles and levers of the switches at junctions shall be brought together under cover upon a properly constructed stage with glass sides, .... enclosing the apparatus. They should be so arranged that, while the signals are at danger, the points shall be free to move ; that the signal-man shall be unable to lower his signal for the approach of a train until after he has set the points in the proper direction for it to pass ; that it shall not be possible for him to exhibit at the same moment any two signals that can lead to a collision between two trains; and that after having lowered his signals to allow a train to pass, he shall not be able to move his points so as to cause an accident, or admit of a collision between two trains. Every signal-man should be able to see the arms and lamps of his home as well as his distance signals, and the working of his points.”
The system devised by Messrs. Saxby and Farmer, of London, and exhibited in the English department at the Exposition, seems to satisfy the requirements of this regulation and is a great improvement upon all systems yet used. It was exhibited at Paris in 1867, and since then has been thoroughly tested and adopted on the best English lines.
In order to understand the application of this apparatus, it may be well to examine a simple case, where, as in Figure 3, Plate I., a branch line starts from a double track main line. The relations of the tracks are easily comprehended from the figure. There are switches at 5 and 6, with their corresponding home signals | and 4, and distance signals at 1, 2, and 9. The machinery for operating these (Figures 1, 2, Plate I.) is contained in a glass house, which is raised from the ground, so that the operator can easily command a view of the tracks in every direction.
For the case under consideration there are nine levers used, which are connected with signals or switches as the case may be. Their uses are shown by reference to the fol-