Canary in the coal mine
A “canary in the coal mine” is an early warning sign of danger or failure, originating from the 20th-century mining practice of using caged birds to detect lethal, odorless gases like carbon monoxide before they affected miners. It signifies a sensitive indicator that signals impending, larger-scale trouble. Cambridge Dictionary +3 According to America.gov, miners once brought canaries into coal mines because … Read more