Canary in a coalmine

Posted by Bob on March 20, 2000

In Reply to: Canary in a coalmine posted by Amer Syed on March 20, 2000

: Can someone tell me what the meaning of the phrase "Canary in a coalmine" is?

There's always a danger of toxic fumes seeping into a mine, so it used to be the practice to keep canaries in coal mines as low-tech poison gas detectors: when the fumes collected, the birds died.