Prepared in connection with his lectures as Professor of Perspective at the Royal Academy, Turner’s diagram is based on a plate from Dr Brook Taylor’s Method of Perspective Made Easy; both in Theory and Practice: in Two Books (London 1768, vol.II, pl.IV, fig.4) by John Joshua Kirby (1716–74). Kirby used it to show how to find the representation ‘of an equilateral triangle, one of whose sides is parallel to the picture. Method 3. By having only one side given’.1 According to Maurice Davies, this diagram corresponds to a section of Turner’s lecture manuscripts containing various notes on methods, primarily based on Kirby, which would have been used to support other lecture texts when further examples of perspective were required.2
Blank, save for an inscription by an unknown hand in pencil ‘34’ bottom left.
Supported by The Samuel H. Kress Foundation