Paper, 'An account of an optical experiment made before the Royal Society on Thursday 6 and 13 December 1722' by J T [John Theophilus] Desaguliers Desaguliers writes: 'Sir Isaac Newton, in his Optics, relates an Experiment made with a Card, or Paper red on one half and blue on the other, painted red on one half and blue on the other, which being enlighten'd by a Candle, the Image, by the Interposition of a Lens, is so projected on a white Paper, held on the other side of the Lens, that the Place where the blue half appears distinct, (or as the Opticians term it, the distinct Base of the Image of the blue half) is much nearer to the Lens than the Place of the Image of the red half.' Subject: Physics Read to the Royal Society on 20 December 1722 Published in Philosophical Transactions as 'An account of an optical experiment made before the Royal Society, on Thursday, Dec. 6th, and repeated on the 13th, 1722.' 1722