Model of spectrum experiments, 1753.
© Science Museum / Science & Society Picture Library
Dr Stephen Demainbray (1710-1782), a science lecturer of the 18th century, devised this 'optical machine' as poor weather often prevented experiments on sunlight. It represented experiments on the spectrum of sunlight using prisms. In each the light represented by a thread which is now mising, entered through a wooden pinhole, and was split into colours by the prism. The model shows different experiments with the coloured rays.