Canaries as Gas Detectors

MANY coal miners have lost their lives through carbon monoxide poisoning during underground fires after explosions. A reliable detector for this lethal gas was needed. Small creatures such as birds and mice are more sensitive to carbon monoxide poisoning than are humans. If the atmosphere became contaminated by carbon monoxide, they collapsed more quickly than humans, thus giving ample warning of the danger.

In 1911 a law was passed in Britain obliging each coal mine to have two finches or mice that could be taken underground by rescuers if a fire occurred. But mice sometimes fell asleep on the floor of their cage, and the miner was unable to tell whether the animal was merely sleeping or had succumbed to the deadly gas. Finches, on the other hand, remained on their perches even when asleep. But when overcome by poisonous gas, they fell from their perch, giving the necessary warning to the miner. A small bottle of oxygen might be kept on hand to resuscitate the affected bird.

The accompanying background photo shows the birds used at Sengheydd, Wales, about 1913, after an explosion and fire had killed 440 men.

In many mines today, though, finches and canaries are being replaced by chemical and electronic devices, and some miners are permitted to provide new homes for the unemployed birds. Pairs of canaries or finches are still kept in some British mines for use as gas detectors.