Letter, from Christian Huygens to Robert Moray, dated at the Hague Discussing the property of colours; discussing his new pendulum clock; discussing an instrument for measuring the descent of bodies (figure in text); discussing new observations of Saturn (figure in text) from a book sent to him with a letter from Rome Read to the Royal Society on 31 August 1664 Pencil note reads that the pages are 'inverted' ie not in the correct reading order 29 August 1664