Presentation of Bird, canary in cage as being used in coal mines for gas detection. Coal Mine museum, Oranje Nassau, Heerlen, Limburg, Netherlands Stock Photo - Alamy
Experience Barnsley: Museum & Discovery Centre - A Haldane humane canary cage - Used in coal mining the cage would have contained a canary to detect toxic gas in the mines. It
canary in a coal mine - Wiktionary, the free dictionary
Lot - Kentucky Folk Art- "Canary in the Coal Mine" Bird Cage
CANARY IN A COAL MINE | Coachella Valley Weekly
The Canary In The Coal Mine Isn't Ancient History
Even 'Canary in the Coal Mine' Indicators Say This Bull Market Is Mostly Healthy - Barron's