A Home Made Rainbow
Probably you have made rainbows in the garden many a time by playing the hose-pipe on the flowers while the sun was shining. It only requires a little experimenting to get the correct angle for the jet of water, and you have a quite decent rainbow in miniature. But here is a much better way, though it is not so simple as the above. In the daytime, when the sun is shining, darken a room by pinning thick brown paper over the window frame.
When the room is quite free from all light, prick a fairly large pin hole through the paper screen and so let in one beam of light. In front of this hold a globular waterbottle full of water. The beam shines on the bottle and the light is reflected back on to the screen, where it is split up into all its beautiful colours in the form of a complete rainbow.