The whole page is taken up with the diagram, with notes above and below it:
but when it is considered that the Sun disk | [blank] miles in broad efulgence [‘miles distant’ inserted above] is opposed to a | column only 20 feet from the ground it cannot | be possible for the sun is below the Horizon | or more accuratly [?shining] <is upon the> [‘all these line are Horizontal line’ inserted above] | to shine and ceases to shine to us before he | appears upon those [?times].
Here there is a large gap with a tiny diagrammatic outline of St Paul’s Cathedral towards the left of the horizon line, and slight vertical and curving lines on the right-hand side, captioned:
supposing St Pauls for instance placed in | the same degree of distance opposed to the | Parrl [sic] ray, how can they in any way [?strike]
The whole passage follows on from the verso of this leaf (
D07509), and continues on the opposite page, folio 89 verso (
D07507). It is part of a sequence beginning on folio 91 verso (
D07511), and running back to folio 82 verso (
D07493). John Gage has discussed these provisional notes (not developed in the perspective lectures) as an example of Turner’s close observation of natural phenomena,
1 in this case the question of sunlight travelling in parallel lines or otherwise, responding to a chapter of
The Art of Painting by Gérard de Lairesse (1640–1711), in the English translation by John Frederick Frisch (London 1738 and later editions).
2 See under
D07511 for a discussion of Lairesse’s text. Maurice Davies has registered Turner’s notes as ‘on light and shadow’, as part of a longer sequence running back to folio 72 verso (
D07473).
3
