A show is an older mining term for the faint blue halo or cap that appears above the flame of a safety lamp when combustible gases are present. Miners used the height and color of this secondary flame to estimate the concentration of methane in the air. A large show meant imminent danger of an explosion.
Heard on the job
The deputy checked the roof cavity and got a distinct show on his lamp, so he pulled the crew back.
Insider tip
Before electronic gas detectors, reading the show on a flame lamp was a critical survival skill for underground deputies.
Also heard as
- cap
- bluecap