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Okay, my challenge in this particular programme was to try and make a light source to go into a mine. And batteries are one option, obviously, but you know you can check a torch with a battery in it and it looks okay and then it can just fail. So I wanted something that didn’t rely on batteries, so the obvious thing is to make a generator.

Now of course we’ve made a generator in the first programme, so why not use that? The trouble with motors and generators is that they have a coil that moves in a magnetic field, and the coil moves, so you have to have a sliding contact, and there’s two problems with that. One is that if it gets wet it ruins the contact and doesn’t work properly and, secondly, when it spins round it sparks. So these are two things you don’t want in a mine where you might have explosive gases and you’ve got lots of water.

So we wanted to make a generator which had no moving electrical parts so we move the magnets instead, and that’s completely okay for the physics. So that’s what we did. And also the other thing is usually with generators you encase the whole thing in metal to make it very efficient, but the trouble with that is that the magnets obviously get attracted to the metal so it’s hard to turn.

So I didn’t want to use any of those efficiency methods, you just wanted it to be a coil of wire and a magnet, and the magnet spins, and that’s the easiest way of spinning it. So we made that and on the first day I think it worked, it was just about glowing the bulb but not much. And then I played around on the second day getting it more efficient and just changing the dimensions and adding a few more magnets, and we got it so that we could light the bulb really nicely.

And then we managed to get some really small bulbs which glowed really well and it was really looking good. Today, good grief, what a day. Well today was really trying to find ways to automate the generator, and on the face of it you know that the Victorians had little clockwork toys and things, it shouldn’t have been too hard.

But of course it’s a lot to learn in a couple of days, so I sort of in the back of my mind thought that I could find some way of doing it but I didn’t really know exactly what I was doing. So I just played around with different things. I think I’ve played around with elastic bands, with springs, springs in a couple of different ways. And then I remembered that clocks have this sort of band as a spring, the thing you wind up, so I tried making one of those but the metal wasn’t springy enough so it didn’t really work at all.

And then, it was just wonderful, I realised that a tape measure pings back when you let go of it. And there’d been a tape measure just three foot away from me for the whole of the three days. And so it was just like, you know, it was a eureka moment because they obviously in some way managed to continuously move the ruler all the way through the little mechanism. So I took open the tape measure, and actually inside the tape measure is a little black spring, made of this incredibly springy, strong material, and that was absolutely what I was looking for. And I put that in and by playing around a little bit we got it to work. It was just wonderful.

So that was the testing and getting that to work, and that worked lovely because instead of just moving the thing for a few seconds like I got before it would move it for, you know, half a minute or something so that was just wonderful. And we put a different bulb on, a little bulb, and that was much brighter. And then I managed to, Hermione and I did all that, the clockwork mechanism, so that was really lovely, and then she put the lights on the hats and made little reflectors for it, and they looked really good.

And so we were all wired together and then we went down the mine which was incredibly wet. So that was great, it was a wonderful, wonderful day. And we had a few problems in the mine so I had to try and fix the thing which wasn’t easy, but luckily we had the cans and everything to give us a little bit of light. And it’s a fairly simple thing so it was easy enough to fix, and nothing major happened, we didn’t break any wires or anything which would have been much more difficult, so it was just a case of fiddling around and getting it to work.

And it was just another Rough Science has flown by. I think this series is just going to go so quickly because it’s such fun.