REPORT OF MR. HOWE OX RAILWAY SWITCHES, ETC. 495
Fig. 3, PI. I.), and inform the engineer that the way is clear. By this movement, the levers 1 and 4, which work the signals for the branch up, are locked, by means of a sliding bar (Fig. 4, PI. I.), and cannot be moved until lever 5 has been pulled, the main track closed, the distance and home signals at 2 and 3, Fig. 3, placed at " danger,” and a junction effected with the branch. Yet levers 6, 7, 8, 9 can be used, because they affect the main and branch down lines, and do not interfere at all with the train in question. The following table gives the combinations which allow the passage of trains over the four tracks :—
To allow a Train to pass on the—
Pull forward
Levers—
1. Main Up, ....
2, 3.
r
6.
2. Main Down, . . .<
9, 8.
f
5.
3. Branch Up, . . . •<
1, 4.
4. Branch Down, .
9, 7.
The following levers will be locked :
5 cannot be pulled forward. Therefore 1 and 4 are locked.
1,4, 7.
5 cannot be pulled forwai'd.
6 cannot be pulled backward.
2, 3, 8.*
5 cannot be pulled backward.
6 cannot be pulled forward.
6 cannot be pulled forward.
* At the first sight one would think that lever 9 in this case ought to be locked, but a glance at the track will show that a train coming down the main track would be carried off on the branch, since switch 6 is in its normal position, and there would be no interference with the branch up-track.
Any one of these combinations can be arranged by one man in a few seconds, as it seems, without the possibility of a mistake.
Every one has probably noticed the tendency of cars passing over a switch to lurch to one side of the track, sometimes with sufficient force to move the switch rails from their position. Some way of guarding against this contingency is therefore necessary. Many contrivances are in use, which are under the direct control of the sigual-man, and which therefore afford only a conditional security. The one adopted by Messrs. Saxby and Farmer cannot be moved during the transit of the train. This " safety locking apparatus ” is rep-