The page comprises a sequence of three roughly cuboid solids or frameworks in perspective from top to bottom at left, with lines running from those above and below to a vanishing point on a horizon line through the central cube halfway down the page. These are respectively labelled to their right, from top to bottom down the centre of the page: ‘Anoptica’, ‘Optica’ and ‘Catoptia’ (sic). There is a further cube to the top right, with lines running diagonally to the same vanishing point, and a vertical rectangle at the bottom right, which has not been produced towards the vanishing point.
Jerrold Ziff has identified this diagram as deriving from the 1598 English edition of Giovanni Paolo Lomazzo’s Tracte Containing the Artes of Curious Paintinge Carvinge & Buildinge (see the sketchbook Introduction).1 Diagram ‘N’ appears on page , in ‘The Fifth Booke: Of the Perspectives’, between chapter X, ‘Of Anoptica the First Sight or Reall and Upper Line’ (page 203) and chapter XI, ‘Of Optica the Second Sight or Reall Middle and Direct Line’ (page 205); chapter XII, ‘Of Catoptica the Third Sight or Reall and Lower Line’ follows on page 206.
The right-hand part of the diagram shows six open, cuboid frameworks, with dotted lines produced from them all, leading to a single vanishing point labelled ‘a’, seen through the cube at centre left; the three levels are labelled ‘Anoptica’, ‘Optica’ and ‘Catoptica’. The upper faces of the two lower cubes each have diagonals drawn across them from the front left corner; these diagonals, each labelled ‘c’ are produced to a common point labelled ‘b’, on the horizon line beyond the cubes on the right.
Turner used the sketch as the basis of his perspective lecture diagram 13 (Tate D17027; Turner Bequest CXCV 57), which shows three cubes on the left, head on, and three to the right, receding in perspective towards the centre left, and labelled from top to bottom ‘ANTIOPTICA’, ‘OPTICA’ and ‘CATIOPTICA’ (sic). He headed the finished diagram ‘LAMATIUS and MOXON’, but it seems to have no connection with the text or diagrams in Joseph Moxon’s Practical Perspective, or Perspective Made Easy ... (London 1670);2 see also the entry for D17027. Maurice Davies observes thatTurner made the gratuitous error in his lectures of pairing Moxon’s vaguely similar-sounding but completely unrelated terms ‘optics’, ‘catoptrics’ and ‘dioptrics’ (for direct, reflected and refracted light) with Lomazzo’s three angles of vision.3
Ziff 1984, p.49 note 6; see also Davies 1992, p.107 note 32, and Davies 1994, p.209; Lomazzo also checked directly.
Davies 1992, p.107 note 32 (for Turner’s lecture diagram see fig.25); Davies 1994, p.297 note 16.
Davies 1994, p.46.
Ibid., pp.41–2, citing Turner’s ‘Royal Academy Lectures’, circa 1807–38, Department of Western Manuscripts, British Library, London, ADD MS 46151 D folio 1 verso.