Illustration taken from the Royal Society Journal, Edinburgh. Sir David Brewster (1781-1868) played a leading part in the popularisation of science in Britain in the 19th century and is chiefly remembered for his work in optics. Solar light is made up of electromagnetic waves emitted by the sun. These vary in wavelength from long-wave radio waves, through infra-red waves and visible light, to ultraviolet waves, X-rays and gamma radiation.
© Science Museum / Science & Society Picture Library