Electric String.

I have never seen the point of infrared motion sensors. Particularly the kind that sound an alarm when they detect something. So what? Someone or something, perhaps a mouse, set off a motion sensor in a room nobody was in and no camera was filming. It means nothing. Besides, if ghosts set off infrared motion sensors, why aren't burglar alarms going off all over the place? They all use the same sensors.

The presence of a ghost is almost always accompanied by a reduction in temperature. They absorb heat, they don't reflect it. They will do the same with infrared. We need an alternative kind of motion sensor.

Sometimes they might appear on film. Or maybe not. If not, then filming any kind of sensor that covers a whole room is no use. Something out-of-shot could have triggered it. No, the detector must be completely in shot and only activated by something that's also in shot. Whether you can see the ghost or not on the film, the sensor must be arranged such that nobody out of shot could have affected it.

So I bought some electric string. Perhaps better known as flexible electroluminescent filament but I prefer to call it electric string. It's quicker. This is sold as a toy, really, and kids use it to light up their bikes or stitch along the sleeves of their jackets. What I have here is one battery-powered unit capable of running one to four electric strings. Each filament is about a metre long. I attached four. Cost, I don't remember but it was peanuts.

I tried this out last night. The battery box sat on a table in the middle of the room and the strings I set out in four directions to the walls. Then I set up two video cameras so that they could see the strings and each other. So, it was not possible to tamper with either the strings or the cameras without being caught.

The strings were not taut. They were loose enough so that anyone - alive or dead - brushing them would make them move. In this instance there was no movement but the night was not wasted. The batteries died after eight hours - I have it on film - and the electric string was visible throughout the night. So I know I have eight hours' worth of illuminated motion detector I can leave to check for movement when I'm not around, and since it's both filmed and illuminated I'll know for sure if a mouse moves it.

If I can work out how, I'll post some snippets of film. The video editing programs I have are designed for film makers and I'm not one, so it could take a day or two and some very, very bad words before I work out how to do it.