Reference no.: D40024 Turner produced this drawing of a transparent globe, along with others of globes of different materials, 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-a-transparent-globe-half-filled-with-d40024)