Maurice Davies has listed the studies here and on folios 21 recto opposite and 21 verso (D07991, D07992) as ‘Perspective or reflective constructions’1 in relation to the preparations for Turner’s perspective lectures, delivered at the Royal Academy from January 1811 onwards (see the Introduction to the sketchbook). The three diagrams grow progressively more complex.
Davies 1994, p.290.
The left-hand (outer) edge of the page is irregular, and appears to be the untrimmed edge of the larger sheet folded to form this and adjacent leaves. At its widest at the top, the leaf is about 2 mm narrower than the usual 117 mm of the regularly trimmed leaves comprising the rest of the sketchbook. The bottom left corner is missing to the extent of about 5 x 5 mm, though again this appears due to the irregularity of the sheet rather than subsequent loss. Folio 43 (D08015) has a similarly irregular edge, as does folio 64 (D08043).