Coal mining is a difficult, dangerous job. 200 years ago, is was even more difficult, and far more dangerous. Deep underground the air is very hot, and there’s also a danger of methane gas. Some of this comes from… well, from us. But down a mind there can be rather more. So if there’s a naked flame around…

Boom! Underground explosions are, traditionally, rather bad for miners. And flammable gases aren’t the only ones you need to worry about – there are also poisonous gases.

That’s where canaries come in. Canaries are sweet little birds – so this is obviously a model.

Small birds like canaries are far more sensitive to poisonous gases than humans are. So miners would take canaries down into the mines with them, and when the canary started to feel a little under the weather…

…they knew the poisonous gases were building up, and it was time to do something about them. But what can you do?

Well, here’s a model coal mine. There are two shafts, one at each side, and a working coal face between them.

The smoke represents the poisonous and flammable gases, accumulating in the coal mine.

And this is a bonfire. Well, it’s a little oil lamp, but to scale, it’s a bonfire, OK?

In goes the bonfire to the bottom of one of the shafts.

…and the rising hot air above the bonfire sets up a circulation through the mine. Here, the air rises up the right-hand mine shaft, which draws fresh air in down the left-hand shaft. That flow of air flushes the flammable and toxic gases out of the mine.
So that’s how you miners can get a breath of fresh air – with a bonfire.