Joseph Mallord William Turner

Lecture Diagram: An Equilateral Triangle Flat on the Ground, with Sides Parallel to the Picture


In Tate Britain

Prints and Drawings Room

View by appointment
Joseph Mallord William Turner 1775–1851
Graphite and watercolour on paper
Support: 586 × 874 mm
Accepted by the nation as part of the Turner Bequest 1856
Turner Bequest CXCV 7

Catalogue entry

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
Kirby 1768, Book II, p.9.
Turner, ‘Royal Academy Lectures’, circa 1807–38, Department of Western Manuscripts, British Library, London, ADD MS 46151 AA folio 31.
Technical notes:
Peter Bower writes that the sheet is Colombier size Whatman paper made by William Balston, at Springfield Mill, Maidstone, Kent.1
Notes in Tate catalogue files.
Blank, save for an inscription by an unknown hand in pencil ‘34’ bottom left.

Andrea Fredericksen
June 2004

Supported by The Samuel H. Kress Foundation

Revised by David Blayney Brown
January 2012

Read full Catalogue entry

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