Sir William Bragg, O.M., K.B.E., F.R.S.

In his third talk tonight Sir William Bragg will show how sunlight is a mixture of ether waves of various wavelengths. Any change in its composition generally breaks away into colour. Most things reflect some wavelengths better than others; so that most things are coloured.

Our perception of colour depends not only on the composition of light, but also on its reception by the eye and its interpretation by the brain processes which are affected by various circumstances.