- All through the old mining areas of Northwest Wales,
if you know where to look, you can find rock cannon.
This is the best known one
in what's now a tourist town called Betws-y-Coed.
Rock cannon are big lumps of rock with small holes drilled into them.
And in the 19th century,
if there was something to be celebrated in a mining town round here,
locals would light fireworks, bonfires, and also fire rock cannon.
Put gunpowder in the little holes,
connect them up with more gunpowder,
either in little channels or by sticking it on with goose grease.
Stick a feather in one end as a fuse, light it, and stand well back.
There are more than 200 rock cannon around Wales
and they were used for all sorts of events.
Visiting royalty? Greeted by rock cannon.
Big wedding to celebrate? Rock cannon.
First train on a new railway? Rock cannon.
It wasn't an everyday thing,
but it definitely wasn't once in a lifetime either.
It doesn't happen much any more, sadly.
They more or less faded out in the mid-20th century.
Most of the mines have closed
and far fewer people have ready access to explosives these days.
I did consider asking if I could bring some gunpowder and fire a cannon,
but an Englishman coming to North Wales
and saying, "Can I put gunpowder in your historical artefacts
"and create a big explosion in the middle of a national park"
is... not a good look? So instead...
...I asked the explosives engineer I know
if he'd be able to build one, out here on the test range.
And he said yes, but... it's two months later.
And I don't think either of us realised quite
how much work this was going to be.
For him.
- I was expecting to cast it one day, and then a week later
come back and just pull the bits out and: all ready to go.
It ended up being three or four weekends
and a great deal of blood, sweat, and tears.
I started off by making some moulds.
So they're just bits of dowel chopped off and nailed onto some boards
with the right spacings. I waxed all of these pieces,
so they should extract, nice and easily, out of the concrete.
We then came to cast the concrete.
We had to get a digger in to spread it around.
We then placed the boards on with these pegs,
pushed down into the concrete.
I then came back the following weekend to remove the boards
and to pull the pegs up, 'cause they'd been nicely waxed.
So they should pull out that easily.
They did not pull out that easily.
I eventually came back the weekend after, got them all out.
Then it rained for all of May.
But we're here now!
And once we're done with this it's going to get screeded over,
so I'll never have to see it again!
Back in the day, the Welsh miners would use goose quill.
It was the only sort of natural tube you could find.
So they'd chop a piece of goose quill,
fill it full of gunpowder,
and then when you light one end of it,
it'll burn incrementally from that end down
and then squirt a bit of flame out of the other end.
And that's what they would then put down each of the holes.
What I've done is then put some black powder
at the bottom of the hole, goose quill into that,
tamp the black powder down,
then a little bit of newspaper to separate it out.
The channels between all the holes are linked up with black powder.
The definitive source for information about Welsh rock cannons is a book
by Griff R. Jones called "The Rock Cannon of Gwynedd".
The book actually had a scale map of Betws-y-Coed cannon in it.
So I was able to scan that.
Each hole's accurate to within about an inch
of where they were on the real thing.
- So: shot one.
This is an exact replica of the cannon at Betws-y-Coed
and we're going to fire it.
This should be pretty much what a visiting dignitary would hear
echoing round the Welsh valleys as their train rolled into the station.
Let's go.
I mean, that was lovely.
Like, the steady glow
as it went through and then boom, boom, boom for each one.
- Yeah.
- I like how the wads of newspaper just shot up after a while.
- One of the things I really want to stress is
that building rock cannon takes skill.
If you were to chisel the holes in the wrong places
or along the wrong fracture lines,
like in this next test, well. That could be disastrous.
- For a rock cannon,
you want something that is going to maintain the hole
and keep it there and you can reuse it.
Let's say you got this sedimentary rock in multiple layers and you bore that way.
You're going to end up with fracture and stress lines in the rock
where it could easily split apart.
So I've cast some concrete,
that's perfectly been cast in layers just to demonstrate
that if you make a weak rock canon
it will not do the job.
- Right. All cameras rolling. How far away should I be?
- About 20 to 30 yards back.
- Okay, good luck.
I saw the rock split and come back together there.
It was weak because that's the way it's been cast
but the amount of force that bolted that outwards...!
Final test then.
What can we do with modern science?
- Well, I think we can have a few firework effects in,
give it a bit of colour.
We'll reload the 55-shot Welsh cannon and try again.
- Lovely. I can't believe this GoPro's still working.
It's still good.
So I do apologise to the people of Wales.
Not only have a couple of Englishmen copied your historical artefacts,
we've been bold enough to think we might be able
to improve it a bit. We hope you'll forgive us.
And if not, we hope you'll at least enjoy the show.
Right. Are we ready?
- Yup. Good to go.
- Yep, that'll do!
- I think we improved on the Welsh. I'm going to claim that.
- Thank you very much. I'd shake your hands, but...
- We're not allowed to. - Yep.
This is a replica of the cannon of--
[incoherent surprised noise]
There's a hole there.
There's a hole.
Don't fall in the hole.