Letter from John Tyndall, Queenwood to Edward Sabine Reference to [Isaac] Newton’s principle of gravity. Tyndall discusses the link between magnetism and gravitation and refers to his experiments on ‘magnecrystallic’ [sic] action to prove that the attraction of gravity could produce the phenomena similar to ‘magnecrystallic’. Tyndall describes his theory using the example of a disk including a small drawing. Reference to Sabine’s pendulum experiments. Intends to explore the relation between heat and magnetism. 29 February 1852