A SHORT HISTORY

Reading the air
underground.

Coal seams breathe out gas.

Miners called the dangerous mixtures damps. From the early 1800s they read them with flames, wire gauze and small birds, until electronic detectors took over. Britain only ended the use of canaries in December 1986.

1816 the gauze lamp goes underground

Compare the methods

An old brass miner's flame safety lamp with a glass and mesh chimney on a worn wooden bench, softly lit — AI-generated image, not a photograph of a real person or place.

Flames that warn
Birds that warn
Sensors that measure
From candle to sensor

THE SHORT ANSWER

Flames, birds,
then electronics.

Each method answered one question:
is the air safe to breathe, and will it burn?

SAFETY LAMP

A flame in a cage

A metal gauze stopped the lamp's flame from passing out into the mine. If firedamp was drawn in, the flame burned more brightly, warning the miner.

Compare methods

CANARIES

A living warning

Canaries breathe heavily and need a lot of oxygen, so toxic gas affected them first. Britain outlawed them in coal mines in December 1986.

See the numbers

THE DAMPS

Five named dangers

Firedamp burns, blackdamp suffocates, whitedamp poisons, stinkdamp smells of rotten eggs and afterdamp follows an explosion.

Meet the damps

COMPARE THE METHODS

How did miners
spot the gas?

Pick a method to see how it worked. The bar shows how much the method relied on judgement by eye rather than a reading.

Method check

Choose a methodA candle flameA gauze safety lampA canaryGlowing platinum wiresAn electronic detector

A candle flameWatch the tip

With firedamp present, a candle's tip turned bluish-grey and stretched into a deeper blue. But open flames could also ignite the gas.

A gauze safety lampFlame grows brighter

Gauze kept the flame inside. Firedamp made it burn brighter, and later lamps had graduated shields to estimate gas from the flame's height.

A canaryBird shows distress

Toxic gases circulated quickly through a canary's body, so it showed symptoms before levels became critical for miners.

Glowing platinum wires0.5 to 3 percent

A lamp attachment patented in 1902 showed small amounts of firedamp by how many of its platinum wires glowed, from 0.5 up to 3 percent.

An electronic detectorDigital reading

Electronic gas detectors with digital readings replaced canaries, and many modern mines use them instead of flame lamps.

Sources: Science Museum Group collection; National Coal Mining Museum for England; Smithsonian Magazine; Wikipedia, Safety lamp.

Drawn from museum collections and published histories of mine safety.

TWO NUMBERS WORTH KNOWING

A narrow danger zone,
and a late farewell.

One figure on when firedamp explodes,
one on how long canaries stayed underground.

5–15%

Concentration at which firedamp explodes

Firedamp is mostly methane, a highly flammable gas that explodes when its concentration reaches 5% to 15%. At 25% it can cause asphyxiation.

FIREDAMP · METHANE

1986

Year canaries were outlawed in coal mines

Britain officially outlawed canaries in coal mines in December 1986, replacing them with electronic gas detectors that give digital readings.

CANARIES · BRITAIN

The gauze safety lamp was first tested underground on 9 January 1816 at Hebburn Colliery, four years after an explosion at Felling Colliery killed 92 men and boys.

INSIDE THE SAFETY LAMP

Light without
the spark.

The flame safety lamp solved a deadly problem: miners needed light, but open flames ignited firedamp seeping from the coal.

Cool the flame
Metal gauze absorbed the flame's heat, so a flame reaching the gauze failed to pass through and the mine air was not ignited.
Watch the flame
Firedamp drawn into the lamp made the flame burn brighter, a built-in warning.
Refine the mesh
The first mesh had 784 holes per square inch. In 1924 a committee recommended 400, giving 16% to 32% more light.
Hand over to electric
Sealed electric lamps took over lighting, with 294,593 in use in Britain by 1922. Flame lamps stayed on for gas testing.

A dark mine tunnel supported by timber props, lit by a single warm lamp — AI-generated image, not a photograph of a real person or place.

A yellow canary perched inside an old brass and glass cage in a museum display — AI-generated image, not a photograph of a real person or place.

THE DAMPS

Why miners
named their gases.

Damp may come from the German Dampf, meaning steam or vapour. Firedamp is mostly methane. Blackdamp is carbon dioxide and nitrogen with no oxygen, and can suffocate. Whitedamp is air containing carbon monoxide, toxic even at low concentrations.

Stinkdamp carries hydrogen sulphide, named for its rotten egg smell. Afterdamp forms after an explosion and contains carbon monoxide, carbon dioxide and nitrogen.

Questions

Questions people ask

Why were canaries taken into coal mines?

Canaries are small and portable and breathe heavily, needing a lot of oxygen. Toxic gases circulate quickly through their bodies, so they show symptoms before gas reaches levels critical for people.

When did British mines stop using canaries?

Britain officially outlawed canaries in coal mines in December 1986. Electronic gas detectors with digital readings replaced them.

How does a miner's safety lamp work?

Metal gauze surrounds the flame. A flame reaching the gauze fails to pass through, so the gas outside is not ignited. Firedamp drawn into the lamp makes the flame burn brighter.

What is firedamp?

A mine gas that is mostly methane. It explodes when its concentration reaches 5% to 15%, and at 25% it can cause asphyxiation.

What was a canary resuscitator?

A metal-and-glass cage with a vent. When a canary fell, a miner sealed the cage and released oxygen from an attached tank while workers evacuated.

Reading the air
underground.