Item 21 - Letter from George Airy

4 pp.

Royal Observatory Greenwich - Answers WW's queries: when Newton's 'analysis is carried to perfection (i.e. so as to shew Fraunhoffer's lines), it has certainly developed original properties of light... Their existence in the diffraction spectrum tends most strikingly to confirm this. - You may also say that persons who have tried the experiments with great care do not believe in [David] Brewster's changes of colour. - The changes of colour are certainly the only source of his objections'. The French have always associated Thomas Young with the discovery of the undulating theory of light.