Reference no.: D40025 Turner produced this drawing of two transparent globes, along with a few others of globes of differing materials (Tate D17147, D17148, D40024, D40026; Turner Bequest CXCV 176, 177a, d), for a lecture on ‘reflexies’ (reflections) and their relationship to light and shade, to be given as Professor of Perspective at the Royal Academy. See note to D17148 for related lecture texts and sketches and the fact that this diagram and three others were once on a single larger sheet. For Turner’s discussion of reflecting spheres in Lecture 5, and its possible influence on his friend John Soane, see notes to D17147. (http://www.tate.org.uk/art/artworks/turner-lecture-diagram-reflections-and-refractions-in-two-transparent-globes-one-half-d40025)