Joseph Mallord William Turner

Lecture Diagram 24: Real and Apparent Diameters of Spheres (after Thomas Malton Senior)


In Tate Britain

Prints and Drawings Room

View by appointment
Joseph Mallord William Turner 1775–1851
Pen and ink and graphite on paper
Support: 668 x 991 mm
Accepted by the nation as part of the Turner Bequest 1856
Turner Bequest CXCV 68

Catalogue entry

In Lecture 2 as Professor of Perspective at the Royal Academy, Turner concluded his discussion of curvilinear perspective with various problems encountered when depicting curved lines in perspective. Maurice Davies argues that Turner was intrigued by the implications of a theorem formulated by the elder Thomas Malton (1726–1801) on the representation of the sphere because it implied a fundamental difference between vision and perspective.1 Diagram 24 is loosely based on elements from diagrams in Malton’s A Compleat Treatise on Perspective in Theory and Practice on the True Principles of Dr Brook Taylor (1775, pl.VII, figs.33 and 34). It shows, Davies writes, ‘the rays from three spheres to the eye. The upper, darker (black, in fact) of the two lines across the central sphere is its true diameter, while the lower, paler (red) one connects the points where the extreme rays from the eye meet the sphere – the “apparent diameter” that the viewer actually perceives’.2 Further sketches are in Turner’s lecture notes.3
Davies 1992, p.40; Thomas Malton, A Compleat Treatise on Perspective, 1775, p.95; Turner, ‘Royal Academy Lectures’, circa 1807–38, Department of Western Manuscripts, British Library, London, ADD MS 46151 L folios 10 verso–11.
Davies 1994, p.166.
Turner, ‘Royal Academy Lectures’, circa 1807–38, Department of Western Manuscripts, British Library, London, ADD MS 46151 L folios 10 verso, 11.
Technical notes:
Peter Bower states that the sheet is Double Elephant size Whatman paper made by William Balston, at Springfield Mill, Maidstone, Kent. The largest group within the perspective drawings, this batch of paper shows a ‘grid-like series of shadows that can be seen within the sheet in transmitted light. This appears to have been caused by a trial method of supporting the woven wire mould cover on the mould’. Because this is the only batch he has seen with such a feature, Bower believes that ‘it may have been tried on one pair of moulds and for some reason never tried again’. He also writes that it is ‘not the best Whatman paper by any means; the weight of this group is also very variable and the moulds have not been kept clean during use’.1
Notes in Tate catalogue files.
Blank, save for an inscription by an unknown hand in pencil ‘70’ 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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