Electricity

When I was a child, many moons ago I was given as a present a fascinating toy called a Kaleidoscope. For those who are too young to remember it is a long tube into which you look and light comes in the other end. Inside is a circle of mirrors containing loose coloured objects such as beads and glass, the light comes in and creates a colourful pattern. It was all very high tech back then when nobody knew what high tech was.