Genre:

Essay

Subjects:

Disability, Light, Experiment, Public Health

People mentioned:

William Pole

Publications cited:

Pole 1859

    After noting that both John Dalton and John F W Herschel suffered from colour blindness, the article begins with a discussion of recent experiments on light and colour. The spectrum of the rainbow, it has been shown, is made up of 'a number of concentric circular lines of colour' most of which are 'mixtures of some few that are really primitive and pure, and necessarily belong to solar light'. These primitive colours, 'generally supposed to be red, yellow, and blue', are mixed to form the colours of our everyday experience. (404) With this scientific knowledge of the mixtures of colour, the 'strict photologist at once puts [...] down' the artist 'by informing him that he knows nothing of the real state of the case' (405). The beams of white light which emanate from the sun and are received on the retina are formed by 'rays of coloured light'. Colour blindness is caused by 'the optic nerve being insensible to the stimulus of pure red light'. As well as light, however, the rays from the sun that produce heat and chemical action 'are certainly quite as important in preserving life and carrying on the business of the world'. (409) Concludes by advising that 'when children show an unusual difficulty in describing colours' they should be tested at once for the symptoms of colour blindness in order that they do not 'waste time in learning accomplishments or professions which they must always be unable to practise' (410–11).