Sir Isaac Newton: optical experiments. Stipple engraving by R.M. Meadows, 1809, after G. Romney, 1796.

"In the year 1792 if indisposition too often checked his hand his imagination was remarkably active. … he had it in contemplation to form a series of pictures of a similar kind each containing some illustrious character of our country. His Newton displaying the prismatic colours (a picture engraved by the permission of the Reverend John Romney to decorate this volume) was the second and the last subject of this intended series that he actually painted …" (Hayley, op. cit. p. 186). Further comments by Hayley on this painting are on pp. 314-315 and 337