Word Study
block letter |
block of metal |
block off |
block out |
block plane |
block signal
| block system
| block tin
| block up
| block vote
| blockade
block signal
CIDE DICTIONARY
block signal,
One of the danger signals or safety signals which guide the movement of trains in a block system. The signal is often so coupled with a switch that act of opening or closing the switch operates the signal also. [Webster 1913 Suppl.]
For further exploring for "block signal" in Webster Dictionary Online
