View this artwork by appointment, at Tate Britain's Prints and Drawings Rooms
Maurice Davies has identified the source of this diagram as Jacques Aleaume and Etienne Migon, La Perspective speculative et practique, Paris 1643, page 151; it is one of several copied into the Perspective sketchbook which Turner did not use for his perspective lectures.1 He probably consulted the copy at the British Museum (since transferred to the British Library, London).
Turner seems to have copied the diagam (the last in the book) almost at random, making a rough approximation of the original, which is very precisely engraved with various scales along each side as an illustration to the convoluted ‘Probleme XI. Trouver, dans un Tableau, l’apparence de quelque Figure Rectiligne, que ce soit; par la connoissance qui sera donnée, de ses Angles, & de ses Costez’, running from pages 149 to 155.
Davies 1994, pp.98, 289, 310 note 76.