Letter 3881

Desaguliers assesses Mr Brown’s letter in detail, criticizing his theories. He suspects there is ‘subtile medium even finer than Light which serves in the Reflection, Refraction and Inflexion of Light’. Desaguliers discusses this hypothesis, citing Sir Isaac Newton’s ‘Opticks’ as an authority. He then relays his theory of gravity, thoughts on thermometers, and astronomical observations. Desaguliers was the son of French Huguenots who quit France after the revocation of the Edict of Nantes (1685). He was a natural philosopher and engineer, became Sir Isaac Newton’s pupil, was a proponent of Newtonianism, and performed lectures and experiments at the Royal Society (Patricia Fara, Desaguliers, John Theophilus (16831744), Oxford Dictionary of National Biography, Oxford University Press, 2004; online edn, May 2009 [http://www.oxforddnb.com/view/article/7539, accessed 12 July 2013]).