Manuscript, 'An account of some experiments made before the Royal Society concerning the properties of light and colours' by J T [John Theophilus] Desaguliers Desaguliers writes: 'The manner of separating the primitive colours of light of such a degree, that if any one of the separated lights be taken apart, its colour shall be found unchangable, was not published before Sir Is. Newton's Opticks came abroad.' Followed by 4 pages of figures showing angles and spectrum of colours. Subject: Optics Read to the Royal Society in July 1714 Published in Philosophical Transactions as 'An account of some experiments of light and colours, formerly made by Sir Isaac Newton, and mention'd in his opticks, lately repeated before the Royal Society, by J. T. Desaguliers, F. R. S' 1714