Maurice Davies identifies this diagram of a cube and various vanishing points as taken from Guidobaldo del Monte, Perspectivae libri sex, Pesaro 1600, page 135; it was used for Turner’s perspective lecture diagram 29, also labelled (following Thomas Malton’s usage in his perspective writings) ‘UBALDUS | 1600’ (Tate D17043; Turner Bequest CXCV 73).1 Turner probably consulted the copy at the British Museum (since transferred to the British Library, London).
For Turner’s various manuscript notes concerning the diagram, see the entry for D17043. Davies has observed that Turner did not copy any of Guidobaldo’s Latin text, and relied on the diagram alone ‘for all he wrote on the author over the next 15 years’.2 There is another drawing from Guidobaldo on the verso of the present leaf (D07428).
Davies 1992, p.19, showing 1600 source and Turner’s lecture diagram as figs.7 and 6 respectively; Davies 1994, pp.84, 288, with 1600 source and lecture diagram shown as figs.3.1 (diagram within surrounding Latin text) and 3.4 respectively.
Davies 1994, p.85; Guidobaldo del Monte’s method discussed pp.85–7.