Joseph Mallord William Turner

Made in connection with Turner’s lectures as Professor of Perspective at the Royal Academy, this diagram is based on a figure from A Compleat Treatise on Perspective in Theory and Practice on the True Principles of Dr Brook Taylor (1775, pl.XI, fig.56) by the elder Thomas Malton (1726–1802). Malton used it to illustrate Problem XVIII: ‘How to find the perspective representation of a triangle, having the original line given, in any plane, whose intersection and vanishing line is also given, and the place of the eye’.1 ¹ Not knowing its original source, scholars from John Ruskin onwards have positioned the diagram upside down, with the triangle at the top. Suggesting that this diagram might represent a cloud, Judy Egerton continued: ‘the point of view (or point of sight) is the point within the uncompleted circle (or station) at the bottom of the drawing. The longer line across the centre is the horizon line, the shorter line above it is the ground line, and the black triangle is the unidentified flying object in a view (?a cloud)’.2

Verso:

Currently laid down.